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Mercury, ₈₀Hg

Mercury
Appearance	shiny, silvery liquid
Standard atomic weight Ar°(Hg)	200.592±0.003 200.59±0.01 (abridged)[1]
Mercury in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Cd ↑ Hg ↓ Cn gold ← mercury → thallium
Atomic number (Z)	80
Group	group 12
Period	period 6
Block	d-block
Electron configuration	[Xe] 4f14 5d10 6s2
Electrons per shell	2, 8, 18, 32, 18, 2
Physical properties
Phase at STP	liquid
Melting point	234.3210 K ​(−38.8290 °C, ​−37.8922 °F)
Boiling point	629.88 K ​(356.73 °C, ​674.11 °F)
Density (near r.t.)	13.534 g/cm3
Triple point	234.3156 K, ​1.65×10−7 kPa
Critical point	1750 K, 172.00 MPa
Heat of fusion	2.29 kJ/mol
Heat of vaporization	59.11 kJ/mol
Molar heat capacity	27.983 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 315 350 393 449 523 629
Atomic properties
Oxidation states	−2 , +1, +2 (a mildly basic oxide)
Electronegativity	Pauling scale: 2.00
Ionization energies	1st: 1007.1 kJ/mol 2nd: 1810 kJ/mol 3rd: 3300 kJ/mol
Atomic radius	empirical: 151 pm
Covalent radius	132±5 pm
Van der Waals radius	155 pm
Spectral lines of mercury
Other properties
Natural occurrence	primordial
Crystal structure	​rhombohedral
Speed of sound	liquid: 1451.4 m/s (at 20 °C)
Thermal expansion	60.4 µm/(m⋅K) (at 25 °C)
Thermal conductivity	8.30 W/(m⋅K)
Electrical resistivity	961 nΩ⋅m (at 25 °C)
Magnetic ordering	diamagnetic[2]
Molar magnetic susceptibility	−33.44×10−6 cm3/mol (293 K)[3]
CAS Number	7439-97-6
History
Discovery	Ancient Egyptians (before 1500 BCE)
Symbol	«Hg»: from its Latin name hydrargyrum, itself from Greek hydrárgyros, ‘water-silver’
Main isotopes of mercury v e
Iso­tope Decay abun­dance half-life (t1/2) mode pro­duct 194Hg syn 444 y ε 194Au 195Hg syn 9.9 h ε 195Au 196Hg 0.15% stable 197Hg syn 64.14 h ε 197Au 198Hg 10.04% stable 199Hg 16.94% stable 200Hg 23.14% stable 201Hg 13.17% stable 202Hg 29.74% stable 203Hg syn 46.612 d β− 203Tl 204Hg 6.82% stable
Category: Mercury (element) view talk edit | references

Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver and was formerly named hydrargyrum ( hy-DRAR-jər-əm) from the Greek words hydor (water) and argyros (silver).^[4] A heavy, silvery d-block element, mercury is the only metallic element that is known to be liquid at standard temperature and pressure; the only other element that is liquid under these conditions is the halogen bromine, though metals such as caesium, gallium, and rubidium melt just above room temperature.

Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is obtained by grinding natural cinnabar or synthetic mercuric sulfide.

Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, mercury relays, fluorescent lamps and other devices, though concerns about the element’s toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alternatives such as alcohol- or galinstan-filled glass thermometers and thermistor- or infrared-based electronic instruments. Likewise, mechanical pressure gauges and electronic strain gauge sensors have replaced mercury sphygmomanometers.

Mercury remains in use in scientific research applications and in amalgam for dental restoration in some locales. It is also used in fluorescent lighting. Electricity passed through mercury vapor in a fluorescent lamp produces short-wave ultraviolet light, which then causes the phosphor in the tube to fluoresce, making visible light.

Mercury poisoning can result from exposure to water-soluble forms of mercury (such as mercuric chloride or methylmercury), by inhalation of mercury vapor, or by ingesting any form of mercury.

Properties

Physical properties

Mercury is a heavy, silvery-white metal that is liquid at room temperature. Compared to other metals, it is a poor conductor of heat, but a fair conductor of electricity.^[6]

It has a freezing point of −38.83 °C and a boiling point of 356.73 °C,^[7][8][9] both the lowest of any stable metal, although preliminary experiments on copernicium and flerovium have indicated that they have even lower boiling points.^[10] This effect is due to lanthanide contraction and relativistic contraction reducing the radius of the outermost electrons, and thus weakening the metallic bonding in mercury.^[8] Upon freezing, the volume of mercury decreases by 3.59% and its density changes from 13.69 g/cm³ when liquid to 14.184 g/cm³ when solid. The coefficient of volume expansion is 181.59 × 10⁻⁶ at 0 °C, 181.71 × 10⁻⁶ at 20 °C and 182.50 × 10⁻⁶ at 100 °C (per °C). Solid mercury is malleable and ductile and can be cut with a knife.^[11]

Table of thermal and physical properties of liquid mercury:^[12][13]

Temperature (°C)	Density (kg/m^3)	Specific heat (kJ/kg K)	Kinematic viscosity (m^2/s)	Conductivity (W/m K)	Thermal diffusivity (m^2/s)	Prandtl Number	Bulk modulus (K^-1)
0	13628.22	0.1403	1.24E-07	8.2	4.30E-06	0.0288	0.000181
20	13579.04	0.1394	1.14E-07	8.69	4.61E-06	0.0249	0.000181
50	13505.84	0.1386	1.04E-07	9.4	5.02E-06	0.0207	0.000181
100	13384.58	0.1373	9.28E-08	10.51	5.72E-06	0.0162	0.000181
150	13264.28	0.1365	8.53E-08	11.49	6.35E-06	0.0134	0.000181
200	13144.94	0.157	8.02E-08	12.34	6.91E-06	0.0116	0.000181
250	13025.6	0.1357	7.65E-08	13.07	7.41E-06	0.0103	0.000183
315.5	12847	0.134	6.73E-08	14.02	8.15E-06	0.0083	0.000186

Chemical properties

Mercury does not react with most acids, such as dilute sulfuric acid, although oxidizing acids such as concentrated sulfuric acid and nitric acid or aqua regia dissolve it to give sulfate, nitrate, and chloride. Like silver, mercury reacts with atmospheric hydrogen sulfide. Mercury reacts with solid sulfur flakes, which are used in mercury spill kits to absorb mercury (spill kits also use activated carbon and powdered zinc).^[14]

Amalgams

Mercury dissolves many metals such as gold and silver to form amalgams. Iron is an exception, and iron flasks have traditionally been used to trade mercury. Several other first row transition metals with the exception of manganese, copper and zinc are also resistant in forming amalgams. Other elements that do not readily form amalgams with mercury include platinum.^[15][16] Sodium amalgam is a common reducing agent in organic synthesis, and is also used in high-pressure sodium lamps.

Mercury readily combines with aluminium to form a mercury-aluminium amalgam when the two pure metals come into contact. Since the amalgam destroys the aluminium oxide layer which protects metallic aluminium from oxidizing in-depth (as in iron rusting), even small amounts of mercury can seriously corrode aluminium. For this reason, mercury is not allowed aboard an aircraft under most circumstances because of the risk of it forming an amalgam with exposed aluminium parts in the aircraft.^[17]

Mercury embrittlement is the most common type of liquid metal embrittlement.

Isotopes

There are seven stable isotopes of mercury, with ²⁰²
Hg being the most abundant (29.86%). The longest-lived radioisotopes are ¹⁹⁴
Hg with a half-life of 444 years, and ²⁰³
Hg with a half-life of 46.612 days. Most of the remaining radioisotopes have half-lives that are less than a day. ¹⁹⁹
Hg and ²⁰¹
Hg are the most often studied NMR-active nuclei, having spins of 1⁄2 and 3⁄2 respectively.^[6] For the synthesis of precious metals two stable mercury isotopes are of potential interest — the trace isotope ¹⁹⁶
Hg and the more abundant ¹⁹⁸
Hg. Both are «one neutron removed» from ¹⁹⁷
Hg, a radioisotope which decays to ¹⁹⁷
Au, the only known stable isotope of gold. However, the rarity of ¹⁹⁶
Hg and the high energy requirements of nuclear reactions «knocking out» a neutron from ¹⁹⁸
Hg (either via photodisintegration or via a (n,2n) reaction involving fast neutrons), have thus far ruled out practical application of this «real philosopher’s stone».

Etymology

«Hg» is the modern chemical symbol for mercury. It is an abbreviation of hydrargyrum, a romanized form of the ancient Greek name for mercury, ὑδράργυρος (hydrargyros). Hydrargyros is a Greek compound word meaning «water-silver», from ὑδρ— (hydr-), the root of ὕδωρ (hydor) «water», and ἄργυρος (argyros) «silver». Like the English name quicksilver («living-silver»), this name was due to mercury’s liquid and shiny properties.

The modern English name «mercury» comes from the planet Mercury. In medieval alchemy, the seven known metals—quicksilver, gold, silver, copper, iron, lead, and tin—were associated with the seven planets. Quicksilver was associated with the fastest planet, which had been named after the Roman god Mercury, who was associated with speed and mobility. The astrological symbol for the planet became one of the alchemical symbols for the metal, and «Mercury» became an alternative name for the metal. Mercury is the only metal for which the alchemical planetary name survives, as it was decided it was preferable to «quicksilver» as a chemical name.^[18][19]

History

Mercury was found in Egyptian tombs that date from 1500 BC.^[20]

In China and Tibet, mercury use was thought to prolong life, heal fractures, and maintain generally good health, although it is now known that exposure to mercury vapor leads to serious adverse health effects.^[21] The first emperor of a unified China, Qín Shǐ Huáng Dì—allegedly buried in a tomb that contained rivers of flowing mercury on a model of the land he ruled, representative of the rivers of China—was reportedly killed by drinking a mercury and powdered jade mixture formulated by Qin alchemists intended as an elixir of immortality.^[22][23] Khumarawayh ibn Ahmad ibn Tulun, the second Tulunid ruler of Egypt (r. 884–896), known for his extravagance and profligacy, reportedly built a basin filled with mercury, on which he would lie on top of air-filled cushions and be rocked to sleep.^[24]

In November 2014 «large quantities» of mercury were discovered in a chamber 60 feet below the 1800-year-old pyramid known as the «Temple of the Feathered Serpent,» «the third largest pyramid of Teotihuacan,» Mexico along with «jade statues, jaguar remains, a box filled with carved shells and rubber balls».^[25]

Aristotle recounts that Daedalus made a wooden statue of Venus move by pouring quicksilver in its interior.^[26] In Greek mythology Daedalus gave the appearance of voice in his statues using quicksilver. The ancient Greeks used cinnabar (mercury sulfide) in ointments; the ancient Egyptians and the Romans used it in cosmetics. In Lamanai, once a major city of the Maya civilization, a pool of mercury was found under a marker in a Mesoamerican ballcourt.^[27][28] By 500 BC mercury was used to make amalgams (Medieval Latin amalgama, «alloy of mercury») with other metals.^[29]

Alchemists thought of mercury as the First Matter from which all metals were formed. They believed that different metals could be produced by varying the quality and quantity of sulfur contained within the mercury. The purest of these was gold, and mercury was called for in attempts at the transmutation of base (or impure) metals into gold, which was the goal of many alchemists.^[18]

The mines in Almadén (Spain), Monte Amiata (Italy), and Idrija (now Slovenia) dominated mercury production from the opening of the mine in Almadén 2500 years ago, until new deposits were found at the end of the 19th century.^[30]

Occurrence

Mercury is an extremely rare element in Earth’s crust, having an average crustal abundance by mass of only 0.08 parts per million (ppm).^[31] Because it does not blend geochemically with those elements that constitute the majority of the crustal mass, mercury ores can be extraordinarily concentrated considering the element’s abundance in ordinary rock. The richest mercury ores contain up to 2.5% mercury by mass, and even the leanest concentrated deposits are at least 0.1% mercury (12,000 times average crustal abundance). It is found either as a native metal (rare) or in cinnabar, metacinnabar, sphalerite, corderoite, livingstonite and other minerals, with cinnabar (HgS) being the most common ore.^[32][33] Mercury ores often occur in hot springs or other volcanic regions.^[34]

Beginning in 1558, with the invention of the patio process to extract silver from ore using mercury, mercury became an essential resource in the economy of Spain and its American colonies. Mercury was used to extract silver from the lucrative mines in New Spain and Peru. Initially, the Spanish Crown’s mines in Almadén in Southern Spain supplied all the mercury for the colonies.^[35] Mercury deposits were discovered in the New World, and more than 100,000 tons of mercury were mined from the region of Huancavelica, Peru, over the course of three centuries following the discovery of deposits there in 1563. The patio process and later pan amalgamation process continued to create great demand for mercury to treat silver ores until the late 19th century.^[36]

Former mines in Italy, the United States and Mexico, which once produced a large proportion of the world supply, have now been completely mined out or, in the case of Slovenia (Idrija) and Spain (Almadén), shut down due to the fall of the price of mercury. Nevada’s McDermitt Mine, the last mercury mine in the United States, closed in 1992. The price of mercury has been highly volatile over the years and in 2006 was $650 per 76-pound (34.46 kg) flask.^[37]

Mercury is extracted by heating cinnabar in a current of air and condensing the vapor. The equation for this extraction is

HgS + O₂ → Hg + SO₂

In 2005, China was the top producer of mercury with almost two-thirds global share followed by Kyrgyzstan.^[38]: 47 Several other countries are believed to have unrecorded production of mercury from copper electrowinning processes and by recovery from effluents.

Because of the high toxicity of mercury, both the mining of cinnabar and refining for mercury are hazardous and historic causes of mercury poisoning.^[39] In China, prison labor was used by a private mining company as recently as the 1950s to develop new cinnabar mines. Thousands of prisoners were used by the Luo Xi mining company to establish new tunnels.^[40] Worker health in functioning mines is at high risk.

A newspaper claimed that an unidentified European Union directive calling for energy-efficient lightbulbs to be made mandatory by 2012 encouraged China to re-open cinnabar mines to obtain the mercury required for CFL bulb manufacture. Environmental dangers have been a concern, particularly in the southern cities of Foshan and Guangzhou, and in Guizhou province in the southwest.^[40]

Abandoned mercury mine processing sites often contain very hazardous waste piles of roasted cinnabar calcines. Water run-off from such sites is a recognized source of ecological damage. Former mercury mines may be suited for constructive re-use. For example, in 1976 Santa Clara County, California purchased the historic Almaden Quicksilver Mine and created a county park on the site, after conducting extensive safety and environmental analysis of the property.^[41]

Chemistry

All known mercury compounds exhibit one of two positive oxidation states: I and II. Experiments have failed to unequivocally demonstrate any higher oxidation states: both the claimed 1976 electrosynthesis of an unstable Hg(III) species and 2007 cryogenic isolation of HgF₄ have disputed interpretations and remain difficult (if not impossible) to reproduce.^[42]

Compounds of mercury(I)

Unlike its lighter neighbors, cadmium and zinc, mercury usually forms simple stable compounds with metal-metal bonds. Most mercury(I) compounds are diamagnetic and feature the dimeric cation, Hg²⁺
₂. Stable derivatives include the chloride and nitrate. Treatment of Hg(I) compounds complexation with strong ligands such as sulfide, cyanide, etc. induces disproportionation to Hg²⁺
and elemental mercury.^[43] Mercury(I) chloride, a colorless solid also known as calomel, is really the compound with the formula Hg₂Cl₂, with the connectivity Cl-Hg-Hg-Cl. It is a standard in electrochemistry. It reacts with chlorine to give mercuric chloride, which resists further oxidation. Mercury(I) hydride, a colorless gas, has the formula HgH, containing no Hg-Hg bond.

Indicative of its tendency to bond to itself, mercury forms mercury polycations, which consist of linear chains of mercury centers, capped with a positive charge. One example is Hg²⁺
₃(AsF⁻
₆)
₂.^[44]

Compounds of mercury(II)

Mercury(II) is the most common oxidation state and is the main one in nature as well. All four mercuric halides are known. They form tetrahedral complexes with other ligands but the halides adopt linear coordination geometry, somewhat like Ag⁺ does. Best known is mercury(II) chloride, an easily sublimating white solid. HgCl₂ forms coordination complexes that are typically tetrahedral, e.g. HgCl²⁻
₄.

Mercury(II) oxide, the main oxide of mercury, arises when the metal is exposed to air for long periods at elevated temperatures. It reverts to the elements upon heating near 400 °C, as was demonstrated by Joseph Priestley in an early synthesis of pure oxygen.^[14] Hydroxides of mercury are poorly characterized, as they are for its neighbors gold and silver.

Being a soft metal, mercury forms very stable derivatives with the heavier chalcogens. Preeminent is mercury(II) sulfide, HgS, which occurs in nature as the ore cinnabar and is the brilliant pigment vermillion. Like ZnS, HgS crystallizes in two forms, the reddish cubic form and the black zinc blende form.^[6] The latter sometimes occurs naturally as metacinnabar.^[33] Mercury(II) selenide (HgSe) and mercury(II) telluride (HgTe) are also known, these as well as various derivatives, e.g. mercury cadmium telluride and mercury zinc telluride being semiconductors useful as infrared detector materials.^[45]

Mercury(II) salts form a variety of complex derivatives with ammonia. These include Millon’s base (Hg₂N⁺), the one-dimensional polymer (salts of HgNH⁺
₂)
_n), and «fusible white precipitate» or [Hg(NH₃)₂]Cl₂. Known as Nessler’s reagent, potassium tetraiodomercurate(II) (HgI²⁻
₄) is still occasionally used to test for ammonia owing to its tendency to form the deeply colored iodide salt of Millon’s base.

Mercury fulminate is a detonator widely used in explosives.^[6]

Organomercury compounds

Organic mercury compounds are historically important but are of little industrial value in the western world. Mercury(II) salts are a rare example of simple metal complexes that react directly with aromatic rings. Organomercury compounds are always divalent and usually two-coordinate and linear geometry. Unlike organocadmium and organozinc compounds, organomercury compounds do not react with water. They usually have the formula HgR₂, which are often volatile, or HgRX, which are often solids, where R is aryl or alkyl and X is usually halide or acetate. Methylmercury, a generic term for compounds with the formula CH₃HgX, is a dangerous family of compounds that are often found in polluted water.^[46] They arise by a process known as biomethylation.

Applications

Mercury is used primarily for the manufacture of industrial chemicals or for electrical and electronic applications. It is used in some liquid-in-glass thermometers, especially those used to measure high temperatures. A still increasing amount is used as gaseous mercury in fluorescent lamps, while most of the other applications are slowly being phased out due to health and safety regulations. In some applications, mercury is replaced with less toxic but considerably more expensive Galinstan alloy.^[47]

Medicine

Mercury and its compounds have been used in medicine, although they are much less common today than they once were, now that the toxic effects of mercury and its compounds are more widely understood. An example of the early therapeutic application of mercury of was published in 1787 by James Lind.^[48]

The first edition of the Merck’s Manual (1899) featured many mercuric compounds^[49] such as:

Mercury is an ingredient in dental amalgams. Thiomersal (called Thimerosal in the United States) is an organic compound used as a preservative in vaccines, though this use is in decline.^[50] Thiomersal is metabolized to ethyl mercury. Although it was widely speculated that this mercury-based preservative could cause or trigger autism in children, scientific studies showed no evidence supporting any such link.^[51] Nevertheless, thiomersal has been removed from, or reduced to trace amounts in all U.S. vaccines recommended for children 6 years of age and under, with the exception of inactivated influenza vaccine.^[52]

Another mercury compound, merbromin (Mercurochrome), is a topical antiseptic used for minor cuts and scrapes that is still in use in some countries.

Mercury in the form of one of its common ores, cinnabar, is used in various traditional medicines, especially in traditional Chinese medicine. Review of its safety has found that cinnabar can lead to significant mercury intoxication when heated, consumed in overdose, or taken long term, and can have adverse effects at therapeutic doses, though effects from therapeutic doses are typically reversible. Although this form of mercury appears to be less toxic than other forms, its use in traditional Chinese medicine has not yet been justified, as the therapeutic basis for the use of cinnabar is not clear.^[53]

Today, the use of mercury in medicine has greatly declined in all respects, especially in developed countries. Thermometers and sphygmomanometers containing mercury were invented in the early 18th and late 19th centuries, respectively. In the early 21st century, their use is declining and has been banned in some countries, states and medical institutions. In 2002, the U.S. Senate passed legislation to phase out the sale of non-prescription mercury thermometers. In 2003, Washington and Maine became the first states to ban mercury blood pressure devices.^[54] Mercury compounds are found in some over-the-counter drugs, including topical antiseptics, stimulant laxatives, diaper-rash ointment, eye drops, and nasal sprays. The FDA has «inadequate data to establish general recognition of the safety and effectiveness» of the mercury ingredients in these products.^[55] Mercury is still used in some diuretics although substitutes now exist for most therapeutic uses.

Production of chlorine and caustic soda

Chlorine is produced from sodium chloride (common salt, NaCl) using electrolysis to separate the metallic sodium from the chlorine gas. Usually the salt is dissolved in water to produce a brine. By-products of any such chloralkali process are hydrogen (H₂) and sodium hydroxide (NaOH), which is commonly called caustic soda or lye. By far the largest use of mercury^[56][57] in the late 20th century was in the mercury cell process (also called the Castner-Kellner process) where metallic sodium is formed as an amalgam at a cathode made from mercury; this sodium is then reacted with water to produce sodium hydroxide.^[58] Many of the industrial mercury releases of the 20th century came from this process, although modern plants claimed to be safe in this regard.^[57] After about 1985, all new chloralkali production facilities that were built in the United States used membrane cell or diaphragm cell technologies to produce chlorine.

Laboratory uses

Some medical thermometers, especially those for high temperatures, are filled with mercury; they are gradually disappearing. In the United States, non-prescription sale of mercury fever thermometers has been banned since 2003.^[59]

Some transit telescopes use a basin of mercury to form a flat and absolutely horizontal mirror, useful in determining an absolute vertical or perpendicular reference. Concave horizontal parabolic mirrors may be formed by rotating liquid mercury on a disk, the parabolic form of the liquid thus formed reflecting and focusing incident light. Such liquid-mirror telescopes are cheaper than conventional large mirror telescopes by up to a factor of 100, but the mirror cannot be tilted and always points straight up.^[60][61][62]

Liquid mercury is a part of popular secondary reference electrode (called the calomel electrode) in electrochemistry as an alternative to the standard hydrogen electrode. The calomel electrode is used to work out the electrode potential of half cells.^[63] Last, but not least, the triple point of mercury, −38.8344 °C, is a fixed point used as a temperature standard for the International Temperature Scale (ITS-90).^[6]

In polarography both the dropping mercury electrode^[64] and the hanging mercury drop electrode^[65] use elemental mercury. This use allows a new uncontaminated electrode to be available for each measurement or each new experiment.

Mercury-containing compounds are also of use in the field of structural biology. Mercuric compounds such as mercury(II) chloride or potassium tetraiodomercurate(II) can be added to protein crystals in an effort to create heavy atom derivatives that can be used to solve the phase problem in X-ray crystallography via isomorphous replacement or anomalous scattering methods.

Niche uses

Gaseous mercury is used in mercury-vapor lamps and some «neon sign» type advertising signs and fluorescent lamps. Those low-pressure lamps emit very spectrally narrow lines, which are traditionally used in optical spectroscopy for calibration of spectral position. Commercial calibration lamps are sold for this purpose; reflecting a fluorescent ceiling light into a spectrometer is a common calibration practice.^[66] Gaseous mercury is also found in some electron tubes, including ignitrons, thyratrons, and mercury arc rectifiers.^[67] It is also used in specialist medical care lamps for skin tanning and disinfection.^[68] Gaseous mercury is added to cold cathode argon-filled lamps to increase the ionization and electrical conductivity. An argon-filled lamp without mercury will have dull spots and will fail to light correctly. Lighting containing mercury can be bombarded/oven pumped only once. When added to neon filled tubes the light produced will be inconsistent red/blue spots until the initial burning-in process is completed; eventually it will light a consistent dull off-blue color.^[69]

• 

  The deep violet glow of a mercury vapor discharge in a germicidal lamp, whose spectrum is rich in invisible ultraviolet radiation.

• 

  Skin tanner containing a low-pressure mercury vapor lamp and two infrared lamps, which act both as light source and electrical ballast

• 

  Assorted types of fluorescent lamps.

• 

  The miniaturized Deep Space Atomic Clock is a linear ion-trap-based mercury ion clock, designed for precise and real-time radio navigation in deep space.

The Deep Space Atomic Clock (DSAC) under development by the Jet Propulsion Laboratory utilises mercury in a linear ion-trap-based clock. The novel use of mercury allows very compact atomic clocks, with low energy requirements, and is therefore ideal for space probes and Mars missions.^[70]

Cosmetics

Mercury, as thiomersal, is widely used in the manufacture of mascara. In 2008, Minnesota became the first state in the United States to ban intentionally added mercury in cosmetics, giving it a tougher standard than the federal government.^[71]

A study in geometric mean urine mercury concentration identified a previously unrecognized source of exposure (skin care products) to inorganic mercury among New York City residents. Population-based biomonitoring also showed that mercury concentration levels are higher in consumers of seafood and fish meals.^[72]

Skin whitening

Mercury is effective as an active ingredient in skin whitening compounds used to depigment skin.^[73] The Minamata Convention on Mercury limits the concentration of mercury in such whiteners to 1 part per million. However, as of 2022, many commercially sold whitener products continue to exceed that limit, and are considered toxic.^[74]

Firearms

Mercury(II) fulminate is a primary explosive which is mainly used as a primer of a cartridge in firearms.

Historic uses

Many historic applications made use of the peculiar physical properties of mercury, especially as a dense liquid and a liquid metal:

• Quantities of liquid mercury ranging from 90 to 600 grams (3.2 to 21.2 oz) have been recovered from elite Maya tombs (100–700 AD)^[25] or ritual caches at six sites. This mercury may have been used in bowls as mirrors for divinatory purposes. Five of these date to the Classic Period of Maya civilization (c. 250–900) but one example predated this.^[75]
• In Islamic Spain, it was used for filling decorative pools. Later, the American artist Alexander Calder built a mercury fountain for the Spanish Pavilion at the 1937 World Exhibition in Paris. The fountain is now on display at the Fundació Joan Miró in Barcelona.^[76]
• Mercury was used inside wobbler lures. Its heavy, liquid form made it useful since the lures made an attractive irregular movement when the mercury moved inside the plug. Such use was stopped due to environmental concerns, but illegal preparation of modern fishing plugs has occurred.
• The Fresnel lenses of old lighthouses used to float and rotate in a bath of mercury which acted like a bearing.^[77]
• Mercury sphygmomanometers (blood pressure meter), barometers, diffusion pumps, coulometers, and many other laboratory instruments took advantage of mercury’s properties as a very dense, opaque liquid with a nearly linear thermal expansion.^[78]
• As an electrically conductive liquid, it was used in mercury switches (including home mercury light switches installed prior to 1970), tilt switches used in old fire detectors, and tilt switches in some home thermostats.^[79]
• Owing to its acoustic properties, mercury was used as the propagation medium in delay-line memory devices used in early digital computers of the mid-20th century.
• Experimental mercury vapor turbines were installed to increase the efficiency of fossil-fuel electrical power plants.^[80] The South Meadow power plant in Hartford, CT employed mercury as its working fluid, in a binary configuration with a secondary water circuit, for a number of years starting in the late 1920s in a drive to improve plant efficiency. Several other plants were built, including the Schiller Station in Portsmouth, NH, which went online in 1950. The idea did not catch on industry-wide due to the weight and toxicity of mercury, as well as the advent of supercritical steam plants in later years.^[81][82]
• Similarly, liquid mercury was used as a coolant for some nuclear reactors; however, sodium is proposed for reactors cooled with liquid metal, because the high density of mercury requires much more energy to circulate as coolant.^[83]
• Mercury was a propellant for early ion engines in electric space propulsion systems. Advantages were mercury’s high molecular weight, low ionization energy, low dual-ionization energy, high liquid density and liquid storability at room temperature. Disadvantages were concerns regarding environmental impact associated with ground testing and concerns about eventual cooling and condensation of some of the propellant on the spacecraft in long-duration operations. The first spaceflight to use electric propulsion was a mercury-fueled ion thruster developed at NASA Glenn Research Center and flown on the Space Electric Rocket Test «SERT-1» spacecraft launched by NASA at its Wallops Flight Facility in 1964. The SERT-1 flight was followed up by the SERT-2 flight in 1970. Mercury and caesium were preferred propellants for ion engines until Hughes Research Laboratory performed studies finding xenon gas to be a suitable replacement. Xenon is now the preferred propellant for ion engines as it has a high molecular weight, little or no reactivity due to its noble gas nature, and has a high liquid density under mild cryogenic storage.^[84][85]

Other applications made use of the chemical properties of mercury:

• The mercury battery is a non-rechargeable electrochemical battery, a primary cell, that was common in the middle of the 20th century. It was used in a wide variety of applications and was available in various sizes, particularly button sizes. Its constant voltage output and long shelf life gave it a niche use for camera light meters and hearing aids. The mercury cell was effectively banned in most countries in the 1990s due to concerns about the mercury contaminating landfills.^[86]
• Mercury was used for preserving wood, developing daguerreotypes, silvering mirrors, anti-fouling paints (discontinued in 1990), herbicides (discontinued in 1995), interior latex paint, handheld maze games, cleaning, and road leveling devices in cars. Mercury compounds have been used in antiseptics, laxatives, antidepressants, and in antisyphilitics.
• It was allegedly used by allied spies to sabotage Luftwaffe planes: a mercury paste was applied to bare aluminium, causing the metal to rapidly corrode; this would cause structural failures.^[87]
• Chloralkali process: The largest industrial use of mercury during the 20th century was in electrolysis for separating chlorine and sodium from brine; mercury being the anode of the Castner-Kellner process. The chlorine was used for bleaching paper (hence the location of many of these plants near paper mills) while the sodium was used to make sodium hydroxide for soaps and other cleaning products. This usage has largely been discontinued, replaced with other technologies that utilize membrane cells.^[88]
• As electrodes in some types of electrolysis, batteries (mercury cells), sodium hydroxide and chlorine production, handheld games, catalysts, insecticides.
• Mercury was once used as a gun barrel bore cleaner.^[89][90]
• From the mid-18th to the mid-19th centuries, a process called «carroting» was used in the making of felt hats. Animal skins were rinsed in an orange solution (the term «carroting» arose from this color) of the mercury compound mercuric nitrate, Hg(NO₃)₂·2H₂O.^[91] This process separated the fur from the pelt and matted it together. This solution and the vapors it produced were highly toxic. The United States Public Health Service banned the use of mercury in the felt industry in December 1941. The psychological symptoms associated with mercury poisoning inspired the phrase «mad as a hatter». Lewis Carroll’s «Mad Hatter» in his book Alice’s Adventures in Wonderland was a play on words based on the older phrase, but the character himself does not exhibit symptoms of mercury poisoning.^[92]
• Gold and silver mining. Historically, mercury was used extensively in hydraulic gold mining in order to help the gold to sink through the flowing water-gravel mixture. Thin gold particles may form mercury-gold amalgam and therefore increase the gold recovery rates.^[6] Large-scale use of mercury stopped in the 1960s. However, mercury is still used in small scale, often clandestine, gold prospecting. It is estimated that 45,000 metric tons of mercury used in California for placer mining have not been recovered.^[93] Mercury was also used in silver mining.^[94]

Historic medicinal uses

Mercury(I) chloride (also known as calomel or mercurous chloride) has been used in traditional medicine as a diuretic, topical disinfectant, and laxative. Mercury(II) chloride (also known as mercuric chloride or corrosive sublimate) was once used to treat syphilis (along with other mercury compounds), although it is so toxic that sometimes the symptoms of its toxicity were confused with those of the syphilis it was believed to treat.^[95] It is also used as a disinfectant. Blue mass, a pill or syrup in which mercury is the main ingredient, was prescribed throughout the 19th century for numerous conditions including constipation, depression, child-bearing and toothaches.^[96] In the early 20th century, mercury was administered to children yearly as a laxative and dewormer, and it was used in teething powders for infants. The mercury-containing organohalide merbromin (sometimes sold as Mercurochrome) is still widely used but has been banned in some countries such as the U.S.^[97]

Toxicity and safety

Mercury

Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H330, H360D, H372, H410
Precautionary statements	P201, P233, P260, P273, P280, P304, P308, P310, P313, P340, P391, P403[98]
NFPA 704 (fire diamond)	2 0 0

Mercury and most of its compounds are extremely toxic and must be handled with care; in cases of spills involving mercury (such as from certain thermometers or fluorescent light bulbs), specific cleaning procedures are used to avoid exposure and contain the spill.^[99] Protocols call for physically merging smaller droplets on hard surfaces, combining them into a single larger pool for easier removal with an eyedropper, or for gently pushing the spill into a disposable container. Vacuum cleaners and brooms cause greater dispersal of the mercury and should not be used. Afterwards, fine sulfur, zinc, or some other powder that readily forms an amalgam (alloy) with mercury at ordinary temperatures is sprinkled over the area before itself being collected and properly disposed of. Cleaning porous surfaces and clothing is not effective at removing all traces of mercury and it is therefore advised to discard these kinds of items should they be exposed to a mercury spill.

Mercury can be absorbed through the skin and mucous membranes and mercury vapors can be inhaled, so containers of mercury are securely sealed to avoid spills and evaporation. Heating of mercury, or of compounds of mercury that may decompose when heated, should be carried out with adequate ventilation in order to minimize exposure to mercury vapor. The most toxic forms of mercury are its organic compounds, such as dimethylmercury and methylmercury. Mercury can cause both chronic and acute poisoning.

Releases in the environment

Preindustrial deposition rates of mercury from the atmosphere may be about 4 ng /(1 L of ice deposit). Although that can be considered a natural level of exposure, regional or global sources have significant effects. Volcanic eruptions can increase the atmospheric source by 4–6 times.^[100]

Natural sources, such as volcanoes, are responsible for approximately half of atmospheric mercury emissions. The human-generated half can be divided into the following estimated percentages:^{[101][102][103]}

• 65% from stationary combustion, of which coal-fired power plants are the largest aggregate source (40% of U.S. mercury emissions in 1999). This includes power plants fueled with gas where the mercury has not been removed. Emissions from coal combustion are between one and two orders of magnitude higher than emissions from oil combustion, depending on the country.^[101]
• 11% from gold production. The three largest point sources for mercury emissions in the U.S. are the three largest gold mines. Hydrogeochemical release of mercury from gold-mine tailings has been accounted as a significant source of atmospheric mercury in eastern Canada.^[104]
• 6.8% from non-ferrous metal production, typically smelters.
• 6.4% from cement production.
• 3.0% from waste disposal, including municipal and hazardous waste, crematoria, and sewage sludge incineration.
• 3.0% from caustic soda production.
• 1.4% from pig iron and steel production.
• 1.1% from mercury production, mainly for batteries.
• 2.0% from other sources.

The above percentages are estimates of the global human-caused mercury emissions in 2000, excluding biomass burning, an important source in some regions.^[101]

Recent atmospheric mercury contamination in outdoor urban air was measured at 0.01–0.02 μg/m³. A 2001 study measured mercury levels in 12 indoor sites chosen to represent a cross-section of building types, locations and ages in the New York area. This study found mercury concentrations significantly elevated over outdoor concentrations, at a range of 0.0065 – 0.523 μg/m³. The average was 0.069 μg/m³.^[105]

Artificial lakes, or reservoirs, may be contaminated with mercury due to the absorption by the water of mercury from submerged trees and soil.
For example, Williston Lake in northern British Columbia, created by the damming of the Peace River in 1968, is still sufficiently contaminated with mercury that it is inadvisable to consume fish from the lake.^[106][107] Permafrost soils have accumulated mercury through atmospheric deposition,^[108] and permafrost thaw in cryospheric regions is also a mechanism of mercury release into lakes, rivers, and wetlands.^[109][110]

Mercury also enters into the environment through the improper disposal (e.g., land filling, incineration) of certain products. Products containing mercury include: auto parts, batteries, fluorescent bulbs, medical products, thermometers, and thermostats.^[111] Due to health concerns (see below), toxics use reduction efforts are cutting back or eliminating mercury in such products. For example, the amount of mercury sold in thermostats in the United States decreased from 14.5 tons in 2004 to 3.9 tons in 2007.^[112]

Most thermometers now use pigmented alcohol instead of mercury. Mercury thermometers are still occasionally used in the medical field because they are more accurate than alcohol thermometers, though both are commonly being replaced by electronic thermometers and less commonly by galinstan thermometers. Mercury thermometers are still widely used for certain scientific applications because of their greater accuracy and working range.

Historically, one of the largest releases was from the Colex plant, a lithium isotope separation plant at Oak Ridge, Tennessee. The plant operated in the 1950s and 1960s. Records are incomplete and unclear, but government commissions have estimated that some two million pounds of mercury are unaccounted for.^[113]

A serious industrial disaster was the dumping of waste mercury compounds into Minamata Bay, Japan, between 1932 and 1968. It is estimated that over 3,000 people suffered various deformities, severe mercury poisoning symptoms or death from what became known as Minamata disease.^[114][115]

The tobacco plant readily absorbs and accumulates heavy metals such as mercury from the surrounding soil into its leaves. These are subsequently inhaled during tobacco smoking.^[116] While mercury is a constituent of tobacco smoke,^[117] studies have largely failed to discover a significant correlation between smoking and Hg uptake by humans compared to sources such as occupational exposure, fish consumption, and amalgam tooth fillings.^[118]

Sediment contamination

Sediments within large urban-industrial estuaries act as an important sink for point source and diffuse mercury pollution within catchments.^[119] A 2015 study of foreshore sediments from the Thames estuary measured total mercury at 0.01 to 12.07 mg/kg with mean of 2.10 mg/kg and median of 0.85 mg/kg (n=351).^[119] The highest mercury concentrations were shown to occur in and around the city of London in association with fine grain muds and high total organic carbon content.^[119] The strong affinity of mercury for carbon rich sediments has also been observed in salt marsh sediments of the River Mersey mean of 2 mg/kg up to 5 mg/kg.^[120] These concentrations are far higher than those shown in salt marsh river creek sediments of New Jersey and mangroves of Southern China which exhibit low mercury concentrations of about 0.2 mg/kg.^[121][122]

Occupational exposure

Due to the health effects of mercury exposure, industrial and commercial uses are regulated in many countries. The World Health Organization, OSHA, and NIOSH all treat mercury as an occupational hazard, and have established specific occupational exposure limits. Environmental releases and disposal of mercury are regulated in the U.S. primarily by the United States Environmental Protection Agency.

Fish

Fish and shellfish have a natural tendency to concentrate mercury in their bodies, often in the form of methylmercury, a highly toxic organic compound of mercury. Species of fish that are high on the food chain, such as shark, swordfish, king mackerel, bluefin tuna, albacore tuna, and tilefish contain higher concentrations of mercury than others. Because mercury and methylmercury are fat soluble, they primarily accumulate in the viscera, although they are also found throughout the muscle tissue.^[123] Mercury presence in fish muscles can be studied using non-lethal muscle biopsies.^[124] Mercury present in prey fish accumulates in the predator that consumes them. Since fish are less efficient at depurating than accumulating methylmercury, methylmercury concentrations in the fish tissue increase over time. Thus species that are high on the food chain amass body burdens of mercury that can be ten times higher than the species they consume. This process is called biomagnification. Mercury poisoning happened this way in Minamata, Japan, now called Minamata disease.

Cosmetics

Some facial creams contain dangerous levels of mercury. Most contain comparatively non-toxic inorganic mercury, but products containing highly toxic organic mercury have been encountered.^[125][126]

Effects and symptoms of mercury poisoning

Toxic effects include damage to the brain, kidneys and lungs. Mercury poisoning can result in several diseases, including acrodynia (pink disease), Hunter-Russell syndrome, and Minamata disease.

Symptoms typically include sensory impairment (vision, hearing, speech), disturbed sensation and a lack of coordination. The type and degree of symptoms exhibited depend upon the individual toxin, the dose, and the method and duration of exposure. Case–control studies have shown effects such as tremors, impaired cognitive skills, and sleep disturbance in workers with chronic exposure to mercury vapor even at low concentrations in the range 0.7–42 μg/m³.^[127][128] A study has shown that acute exposure (4–8 hours) to calculated elemental mercury levels of 1.1 to 44 mg/m³ resulted in chest pain, dyspnea, cough, hemoptysis, impairment of pulmonary function, and evidence of interstitial pneumonitis.^[129] Acute exposure to mercury vapor has been shown to result in profound central nervous system effects, including psychotic reactions characterized by delirium, hallucinations, and suicidal tendency. Occupational exposure has resulted in broad-ranging functional disturbance, including erethism, irritability, excitability, excessive shyness, and insomnia. With continuing exposure, a fine tremor develops and may escalate to violent muscular spasms. Tremor initially involves the hands and later spreads to the eyelids, lips, and tongue. Long-term, low-level exposure has been associated with more subtle symptoms of erethism, including fatigue, irritability, loss of memory, vivid dreams and depression.^[130][131]

Treatment

Research on the treatment of mercury poisoning is limited. Currently available drugs for acute mercurial poisoning include chelators N-acetyl-D, L-penicillamine (NAP), British Anti-Lewisite (BAL), 2,3-dimercapto-1-propanesulfonic acid (DMPS), and dimercaptosuccinic acid (DMSA). In one small study including 11 construction workers exposed to elemental mercury, patients were treated with DMSA and NAP.^[132] Chelation therapy with both drugs resulted in the mobilization of a small fraction of the total estimated body mercury. DMSA was able to increase the excretion of mercury to a greater extent than NAP.^[133]

Regulations

International

140 countries agreed in the Minamata Convention on Mercury by the United Nations Environment Programme (UNEP) to prevent emissions.^[134] The convention was signed on 10 October 2013.^[135]

United States

In the United States, the Environmental Protection Agency is charged with regulating and managing mercury contamination. Several laws give the EPA this authority, including the Clean Air Act, the Clean Water Act, the Resource Conservation and Recovery Act, and the Safe Drinking Water Act. Additionally, the Mercury-Containing and Rechargeable Battery Management Act, passed in 1996, phases out the use of mercury in batteries, and provides for the efficient and cost-effective disposal of many types of used batteries.^[136] North America contributed approximately 11% of the total global anthropogenic mercury emissions in 1995.^[137]

The United States Clean Air Act, passed in 1990, put mercury on a list of toxic pollutants that need to be controlled to the greatest possible extent. Thus, industries that release high concentrations of mercury into the environment agreed to install maximum achievable control technologies (MACT). In March 2005, the EPA promulgated a regulation^[138] that added power plants to the list of sources that should be controlled and instituted a national cap and trade system. States were given until November 2006 to impose stricter controls, but after a legal challenge from several states, the regulations were struck down by a federal appeals court on 8 February 2008. The rule was deemed not sufficient to protect the health of persons living near coal-fired power plants, given the negative effects documented in the EPA Study Report to Congress of 1998.^[139] However newer data published in 2015 showed that after introduction of the stricter controls mercury declined sharply, indicating that the Clean Air Act had its intended impact.^[140]

The EPA announced new rules for coal-fired power plants on 22 December 2011.^[141] Cement kilns that burn hazardous waste are held to a looser standard than are standard hazardous waste incinerators in the United States, and as a result are a disproportionate source of mercury pollution.^[142]

European Union

In the European Union, the directive on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment (see RoHS) bans mercury from certain electrical and electronic products, and limits the amount of mercury in other products to less than 1000 ppm.^[143] There are restrictions for mercury concentration in packaging (the limit is 100 ppm for sum of mercury, lead, hexavalent chromium and cadmium) and batteries (the limit is 5 ppm).^[144] In July 2007, the European Union also banned mercury in non-electrical measuring devices, such as thermometers and barometers. The ban applies to new devices only, and contains exemptions for the health care sector and a two-year grace period for manufacturers of barometers.^[145]

Norway

Norway enacted a total ban on the use of mercury in the manufacturing and import/export of mercury products, effective 1 January 2008.^[146] In 2002, several lakes in Norway were found to have a poor state of mercury pollution, with an excess of 1 μg/g of mercury in their sediment.^[147]
In 2008, Norway’s Minister of Environment Development Erik Solheim said: «Mercury is among the most dangerous environmental toxins. Satisfactory alternatives to Hg in products are
available, and it is therefore fitting to induce a ban.»^[148]

Sweden

Products containing mercury were banned in Sweden in 2009.^[149][150]

Denmark

In 2008, Denmark also banned dental mercury amalgam,^[148] except for molar masticating surface fillings in permanent (adult) teeth.

See also

• Mercury pollution in the ocean
• Red mercury
• COLEX process (isotopic separation)

References

Further reading

• Johnston, Andrew Scott (15 September 2013). Mercury and the Making of California: Mining, Landscape, and Race, 1840–1890. TotalBoox, TBX. University Press of Colorado. ISBN 9781457183997. OCLC 969039240.

External links

• Chemistry in its element podcast (MP3) from the Royal Society of Chemistry’s Chemistry World: Mercury
• Mercury at The Periodic Table of Videos (University of Nottingham)
• Centers for Disease Control and Prevention – Mercury Topic
• EPA fish consumption guidelines
• Hg 80 Mercury
• Material Safety Data Sheet – Mercury
• Stopping Pollution: Mercury – Oceana
• Natural Resources Defense Council (NRDC): Mercury Contamination in Fish guide – NRDC
• NLM Hazardous Substances Databank – Mercury
• BBC – Earth News – Mercury «turns» wetland birds such as ibises homosexual
• Changing Patterns in the Use, Recycling, and Material Substitution of Mercury in the United States United States Geological Survey
• Thermodynamical data on liquid mercury.
• «Mercury (element)» . Encyclopædia Britannica (11th ed.). 1911.

Mercury, ₈₀Hg

Mercury
Appearance	shiny, silvery liquid
Standard atomic weight Ar°(Hg)	200.592±0.003 200.59±0.01 (abridged)[1]
Mercury in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Cd ↑ Hg ↓ Cn gold ← mercury → thallium
Atomic number (Z)	80
Group	group 12
Period	period 6
Block	d-block
Electron configuration	[Xe] 4f14 5d10 6s2
Electrons per shell	2, 8, 18, 32, 18, 2
Physical properties
Phase at STP	liquid
Melting point	234.3210 K ​(−38.8290 °C, ​−37.8922 °F)
Boiling point	629.88 K ​(356.73 °C, ​674.11 °F)
Density (near r.t.)	13.534 g/cm3
Triple point	234.3156 K, ​1.65×10−7 kPa
Critical point	1750 K, 172.00 MPa
Heat of fusion	2.29 kJ/mol
Heat of vaporization	59.11 kJ/mol
Molar heat capacity	27.983 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 315 350 393 449 523 629
Atomic properties
Oxidation states	−2 , +1, +2 (a mildly basic oxide)
Electronegativity	Pauling scale: 2.00
Ionization energies	1st: 1007.1 kJ/mol 2nd: 1810 kJ/mol 3rd: 3300 kJ/mol
Atomic radius	empirical: 151 pm
Covalent radius	132±5 pm
Van der Waals radius	155 pm
Spectral lines of mercury
Other properties
Natural occurrence	primordial
Crystal structure	​rhombohedral
Speed of sound	liquid: 1451.4 m/s (at 20 °C)
Thermal expansion	60.4 µm/(m⋅K) (at 25 °C)
Thermal conductivity	8.30 W/(m⋅K)
Electrical resistivity	961 nΩ⋅m (at 25 °C)
Magnetic ordering	diamagnetic[2]
Molar magnetic susceptibility	−33.44×10−6 cm3/mol (293 K)[3]
CAS Number	7439-97-6
History
Discovery	Ancient Egyptians (before 1500 BCE)
Symbol	«Hg»: from its Latin name hydrargyrum, itself from Greek hydrárgyros, ‘water-silver’
Main isotopes of mercury v e
Iso­tope Decay abun­dance half-life (t1/2) mode pro­duct 194Hg syn 444 y ε 194Au 195Hg syn 9.9 h ε 195Au 196Hg 0.15% stable 197Hg syn 64.14 h ε 197Au 198Hg 10.04% stable 199Hg 16.94% stable 200Hg 23.14% stable 201Hg 13.17% stable 202Hg 29.74% stable 203Hg syn 46.612 d β− 203Tl 204Hg 6.82% stable
Category: Mercury (element) view talk edit | references

Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver and was formerly named hydrargyrum ( hy-DRAR-jər-əm) from the Greek words hydor (water) and argyros (silver).^[4] A heavy, silvery d-block element, mercury is the only metallic element that is known to be liquid at standard temperature and pressure; the only other element that is liquid under these conditions is the halogen bromine, though metals such as caesium, gallium, and rubidium melt just above room temperature.

Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is obtained by grinding natural cinnabar or synthetic mercuric sulfide.

Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, mercury relays, fluorescent lamps and other devices, though concerns about the element’s toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alternatives such as alcohol- or galinstan-filled glass thermometers and thermistor- or infrared-based electronic instruments. Likewise, mechanical pressure gauges and electronic strain gauge sensors have replaced mercury sphygmomanometers.

Mercury remains in use in scientific research applications and in amalgam for dental restoration in some locales. It is also used in fluorescent lighting. Electricity passed through mercury vapor in a fluorescent lamp produces short-wave ultraviolet light, which then causes the phosphor in the tube to fluoresce, making visible light.

Mercury poisoning can result from exposure to water-soluble forms of mercury (such as mercuric chloride or methylmercury), by inhalation of mercury vapor, or by ingesting any form of mercury.

Properties

Physical properties

Mercury is a heavy, silvery-white metal that is liquid at room temperature. Compared to other metals, it is a poor conductor of heat, but a fair conductor of electricity.^[6]

It has a freezing point of −38.83 °C and a boiling point of 356.73 °C,^[7][8][9] both the lowest of any stable metal, although preliminary experiments on copernicium and flerovium have indicated that they have even lower boiling points.^[10] This effect is due to lanthanide contraction and relativistic contraction reducing the radius of the outermost electrons, and thus weakening the metallic bonding in mercury.^[8] Upon freezing, the volume of mercury decreases by 3.59% and its density changes from 13.69 g/cm³ when liquid to 14.184 g/cm³ when solid. The coefficient of volume expansion is 181.59 × 10⁻⁶ at 0 °C, 181.71 × 10⁻⁶ at 20 °C and 182.50 × 10⁻⁶ at 100 °C (per °C). Solid mercury is malleable and ductile and can be cut with a knife.^[11]

Table of thermal and physical properties of liquid mercury:^[12][13]

Temperature (°C)	Density (kg/m^3)	Specific heat (kJ/kg K)	Kinematic viscosity (m^2/s)	Conductivity (W/m K)	Thermal diffusivity (m^2/s)	Prandtl Number	Bulk modulus (K^-1)
0	13628.22	0.1403	1.24E-07	8.2	4.30E-06	0.0288	0.000181
20	13579.04	0.1394	1.14E-07	8.69	4.61E-06	0.0249	0.000181
50	13505.84	0.1386	1.04E-07	9.4	5.02E-06	0.0207	0.000181
100	13384.58	0.1373	9.28E-08	10.51	5.72E-06	0.0162	0.000181
150	13264.28	0.1365	8.53E-08	11.49	6.35E-06	0.0134	0.000181
200	13144.94	0.157	8.02E-08	12.34	6.91E-06	0.0116	0.000181
250	13025.6	0.1357	7.65E-08	13.07	7.41E-06	0.0103	0.000183
315.5	12847	0.134	6.73E-08	14.02	8.15E-06	0.0083	0.000186

Chemical properties

Mercury does not react with most acids, such as dilute sulfuric acid, although oxidizing acids such as concentrated sulfuric acid and nitric acid or aqua regia dissolve it to give sulfate, nitrate, and chloride. Like silver, mercury reacts with atmospheric hydrogen sulfide. Mercury reacts with solid sulfur flakes, which are used in mercury spill kits to absorb mercury (spill kits also use activated carbon and powdered zinc).^[14]

Amalgams

Mercury dissolves many metals such as gold and silver to form amalgams. Iron is an exception, and iron flasks have traditionally been used to trade mercury. Several other first row transition metals with the exception of manganese, copper and zinc are also resistant in forming amalgams. Other elements that do not readily form amalgams with mercury include platinum.^[15][16] Sodium amalgam is a common reducing agent in organic synthesis, and is also used in high-pressure sodium lamps.

Mercury readily combines with aluminium to form a mercury-aluminium amalgam when the two pure metals come into contact. Since the amalgam destroys the aluminium oxide layer which protects metallic aluminium from oxidizing in-depth (as in iron rusting), even small amounts of mercury can seriously corrode aluminium. For this reason, mercury is not allowed aboard an aircraft under most circumstances because of the risk of it forming an amalgam with exposed aluminium parts in the aircraft.^[17]

Mercury embrittlement is the most common type of liquid metal embrittlement.

Isotopes

There are seven stable isotopes of mercury, with ²⁰²
Hg being the most abundant (29.86%). The longest-lived radioisotopes are ¹⁹⁴
Hg with a half-life of 444 years, and ²⁰³
Hg with a half-life of 46.612 days. Most of the remaining radioisotopes have half-lives that are less than a day. ¹⁹⁹
Hg and ²⁰¹
Hg are the most often studied NMR-active nuclei, having spins of 1⁄2 and 3⁄2 respectively.^[6] For the synthesis of precious metals two stable mercury isotopes are of potential interest — the trace isotope ¹⁹⁶
Hg and the more abundant ¹⁹⁸
Hg. Both are «one neutron removed» from ¹⁹⁷
Hg, a radioisotope which decays to ¹⁹⁷
Au, the only known stable isotope of gold. However, the rarity of ¹⁹⁶
Hg and the high energy requirements of nuclear reactions «knocking out» a neutron from ¹⁹⁸
Hg (either via photodisintegration or via a (n,2n) reaction involving fast neutrons), have thus far ruled out practical application of this «real philosopher’s stone».

Etymology

«Hg» is the modern chemical symbol for mercury. It is an abbreviation of hydrargyrum, a romanized form of the ancient Greek name for mercury, ὑδράργυρος (hydrargyros). Hydrargyros is a Greek compound word meaning «water-silver», from ὑδρ— (hydr-), the root of ὕδωρ (hydor) «water», and ἄργυρος (argyros) «silver». Like the English name quicksilver («living-silver»), this name was due to mercury’s liquid and shiny properties.

The modern English name «mercury» comes from the planet Mercury. In medieval alchemy, the seven known metals—quicksilver, gold, silver, copper, iron, lead, and tin—were associated with the seven planets. Quicksilver was associated with the fastest planet, which had been named after the Roman god Mercury, who was associated with speed and mobility. The astrological symbol for the planet became one of the alchemical symbols for the metal, and «Mercury» became an alternative name for the metal. Mercury is the only metal for which the alchemical planetary name survives, as it was decided it was preferable to «quicksilver» as a chemical name.^[18][19]

History

Mercury was found in Egyptian tombs that date from 1500 BC.^[20]

In China and Tibet, mercury use was thought to prolong life, heal fractures, and maintain generally good health, although it is now known that exposure to mercury vapor leads to serious adverse health effects.^[21] The first emperor of a unified China, Qín Shǐ Huáng Dì—allegedly buried in a tomb that contained rivers of flowing mercury on a model of the land he ruled, representative of the rivers of China—was reportedly killed by drinking a mercury and powdered jade mixture formulated by Qin alchemists intended as an elixir of immortality.^[22][23] Khumarawayh ibn Ahmad ibn Tulun, the second Tulunid ruler of Egypt (r. 884–896), known for his extravagance and profligacy, reportedly built a basin filled with mercury, on which he would lie on top of air-filled cushions and be rocked to sleep.^[24]

In November 2014 «large quantities» of mercury were discovered in a chamber 60 feet below the 1800-year-old pyramid known as the «Temple of the Feathered Serpent,» «the third largest pyramid of Teotihuacan,» Mexico along with «jade statues, jaguar remains, a box filled with carved shells and rubber balls».^[25]

Aristotle recounts that Daedalus made a wooden statue of Venus move by pouring quicksilver in its interior.^[26] In Greek mythology Daedalus gave the appearance of voice in his statues using quicksilver. The ancient Greeks used cinnabar (mercury sulfide) in ointments; the ancient Egyptians and the Romans used it in cosmetics. In Lamanai, once a major city of the Maya civilization, a pool of mercury was found under a marker in a Mesoamerican ballcourt.^[27][28] By 500 BC mercury was used to make amalgams (Medieval Latin amalgama, «alloy of mercury») with other metals.^[29]

Alchemists thought of mercury as the First Matter from which all metals were formed. They believed that different metals could be produced by varying the quality and quantity of sulfur contained within the mercury. The purest of these was gold, and mercury was called for in attempts at the transmutation of base (or impure) metals into gold, which was the goal of many alchemists.^[18]

The mines in Almadén (Spain), Monte Amiata (Italy), and Idrija (now Slovenia) dominated mercury production from the opening of the mine in Almadén 2500 years ago, until new deposits were found at the end of the 19th century.^[30]

Occurrence

Mercury is an extremely rare element in Earth’s crust, having an average crustal abundance by mass of only 0.08 parts per million (ppm).^[31] Because it does not blend geochemically with those elements that constitute the majority of the crustal mass, mercury ores can be extraordinarily concentrated considering the element’s abundance in ordinary rock. The richest mercury ores contain up to 2.5% mercury by mass, and even the leanest concentrated deposits are at least 0.1% mercury (12,000 times average crustal abundance). It is found either as a native metal (rare) or in cinnabar, metacinnabar, sphalerite, corderoite, livingstonite and other minerals, with cinnabar (HgS) being the most common ore.^[32][33] Mercury ores often occur in hot springs or other volcanic regions.^[34]

Beginning in 1558, with the invention of the patio process to extract silver from ore using mercury, mercury became an essential resource in the economy of Spain and its American colonies. Mercury was used to extract silver from the lucrative mines in New Spain and Peru. Initially, the Spanish Crown’s mines in Almadén in Southern Spain supplied all the mercury for the colonies.^[35] Mercury deposits were discovered in the New World, and more than 100,000 tons of mercury were mined from the region of Huancavelica, Peru, over the course of three centuries following the discovery of deposits there in 1563. The patio process and later pan amalgamation process continued to create great demand for mercury to treat silver ores until the late 19th century.^[36]

Former mines in Italy, the United States and Mexico, which once produced a large proportion of the world supply, have now been completely mined out or, in the case of Slovenia (Idrija) and Spain (Almadén), shut down due to the fall of the price of mercury. Nevada’s McDermitt Mine, the last mercury mine in the United States, closed in 1992. The price of mercury has been highly volatile over the years and in 2006 was $650 per 76-pound (34.46 kg) flask.^[37]

Mercury is extracted by heating cinnabar in a current of air and condensing the vapor. The equation for this extraction is

HgS + O₂ → Hg + SO₂

In 2005, China was the top producer of mercury with almost two-thirds global share followed by Kyrgyzstan.^[38]: 47 Several other countries are believed to have unrecorded production of mercury from copper electrowinning processes and by recovery from effluents.

Because of the high toxicity of mercury, both the mining of cinnabar and refining for mercury are hazardous and historic causes of mercury poisoning.^[39] In China, prison labor was used by a private mining company as recently as the 1950s to develop new cinnabar mines. Thousands of prisoners were used by the Luo Xi mining company to establish new tunnels.^[40] Worker health in functioning mines is at high risk.

A newspaper claimed that an unidentified European Union directive calling for energy-efficient lightbulbs to be made mandatory by 2012 encouraged China to re-open cinnabar mines to obtain the mercury required for CFL bulb manufacture. Environmental dangers have been a concern, particularly in the southern cities of Foshan and Guangzhou, and in Guizhou province in the southwest.^[40]

Abandoned mercury mine processing sites often contain very hazardous waste piles of roasted cinnabar calcines. Water run-off from such sites is a recognized source of ecological damage. Former mercury mines may be suited for constructive re-use. For example, in 1976 Santa Clara County, California purchased the historic Almaden Quicksilver Mine and created a county park on the site, after conducting extensive safety and environmental analysis of the property.^[41]

Chemistry

All known mercury compounds exhibit one of two positive oxidation states: I and II. Experiments have failed to unequivocally demonstrate any higher oxidation states: both the claimed 1976 electrosynthesis of an unstable Hg(III) species and 2007 cryogenic isolation of HgF₄ have disputed interpretations and remain difficult (if not impossible) to reproduce.^[42]

Compounds of mercury(I)

Unlike its lighter neighbors, cadmium and zinc, mercury usually forms simple stable compounds with metal-metal bonds. Most mercury(I) compounds are diamagnetic and feature the dimeric cation, Hg²⁺
₂. Stable derivatives include the chloride and nitrate. Treatment of Hg(I) compounds complexation with strong ligands such as sulfide, cyanide, etc. induces disproportionation to Hg²⁺
and elemental mercury.^[43] Mercury(I) chloride, a colorless solid also known as calomel, is really the compound with the formula Hg₂Cl₂, with the connectivity Cl-Hg-Hg-Cl. It is a standard in electrochemistry. It reacts with chlorine to give mercuric chloride, which resists further oxidation. Mercury(I) hydride, a colorless gas, has the formula HgH, containing no Hg-Hg bond.

Indicative of its tendency to bond to itself, mercury forms mercury polycations, which consist of linear chains of mercury centers, capped with a positive charge. One example is Hg²⁺
₃(AsF⁻
₆)
₂.^[44]

Compounds of mercury(II)

Mercury(II) is the most common oxidation state and is the main one in nature as well. All four mercuric halides are known. They form tetrahedral complexes with other ligands but the halides adopt linear coordination geometry, somewhat like Ag⁺ does. Best known is mercury(II) chloride, an easily sublimating white solid. HgCl₂ forms coordination complexes that are typically tetrahedral, e.g. HgCl²⁻
₄.

Mercury(II) oxide, the main oxide of mercury, arises when the metal is exposed to air for long periods at elevated temperatures. It reverts to the elements upon heating near 400 °C, as was demonstrated by Joseph Priestley in an early synthesis of pure oxygen.^[14] Hydroxides of mercury are poorly characterized, as they are for its neighbors gold and silver.

Being a soft metal, mercury forms very stable derivatives with the heavier chalcogens. Preeminent is mercury(II) sulfide, HgS, which occurs in nature as the ore cinnabar and is the brilliant pigment vermillion. Like ZnS, HgS crystallizes in two forms, the reddish cubic form and the black zinc blende form.^[6] The latter sometimes occurs naturally as metacinnabar.^[33] Mercury(II) selenide (HgSe) and mercury(II) telluride (HgTe) are also known, these as well as various derivatives, e.g. mercury cadmium telluride and mercury zinc telluride being semiconductors useful as infrared detector materials.^[45]

Mercury(II) salts form a variety of complex derivatives with ammonia. These include Millon’s base (Hg₂N⁺), the one-dimensional polymer (salts of HgNH⁺
₂)
_n), and «fusible white precipitate» or [Hg(NH₃)₂]Cl₂. Known as Nessler’s reagent, potassium tetraiodomercurate(II) (HgI²⁻
₄) is still occasionally used to test for ammonia owing to its tendency to form the deeply colored iodide salt of Millon’s base.

Mercury fulminate is a detonator widely used in explosives.^[6]

Organomercury compounds

Organic mercury compounds are historically important but are of little industrial value in the western world. Mercury(II) salts are a rare example of simple metal complexes that react directly with aromatic rings. Organomercury compounds are always divalent and usually two-coordinate and linear geometry. Unlike organocadmium and organozinc compounds, organomercury compounds do not react with water. They usually have the formula HgR₂, which are often volatile, or HgRX, which are often solids, where R is aryl or alkyl and X is usually halide or acetate. Methylmercury, a generic term for compounds with the formula CH₃HgX, is a dangerous family of compounds that are often found in polluted water.^[46] They arise by a process known as biomethylation.

Applications

Mercury is used primarily for the manufacture of industrial chemicals or for electrical and electronic applications. It is used in some liquid-in-glass thermometers, especially those used to measure high temperatures. A still increasing amount is used as gaseous mercury in fluorescent lamps, while most of the other applications are slowly being phased out due to health and safety regulations. In some applications, mercury is replaced with less toxic but considerably more expensive Galinstan alloy.^[47]

Medicine

Mercury and its compounds have been used in medicine, although they are much less common today than they once were, now that the toxic effects of mercury and its compounds are more widely understood. An example of the early therapeutic application of mercury of was published in 1787 by James Lind.^[48]

The first edition of the Merck’s Manual (1899) featured many mercuric compounds^[49] such as:

Mercury is an ingredient in dental amalgams. Thiomersal (called Thimerosal in the United States) is an organic compound used as a preservative in vaccines, though this use is in decline.^[50] Thiomersal is metabolized to ethyl mercury. Although it was widely speculated that this mercury-based preservative could cause or trigger autism in children, scientific studies showed no evidence supporting any such link.^[51] Nevertheless, thiomersal has been removed from, or reduced to trace amounts in all U.S. vaccines recommended for children 6 years of age and under, with the exception of inactivated influenza vaccine.^[52]

Another mercury compound, merbromin (Mercurochrome), is a topical antiseptic used for minor cuts and scrapes that is still in use in some countries.

Mercury in the form of one of its common ores, cinnabar, is used in various traditional medicines, especially in traditional Chinese medicine. Review of its safety has found that cinnabar can lead to significant mercury intoxication when heated, consumed in overdose, or taken long term, and can have adverse effects at therapeutic doses, though effects from therapeutic doses are typically reversible. Although this form of mercury appears to be less toxic than other forms, its use in traditional Chinese medicine has not yet been justified, as the therapeutic basis for the use of cinnabar is not clear.^[53]

Today, the use of mercury in medicine has greatly declined in all respects, especially in developed countries. Thermometers and sphygmomanometers containing mercury were invented in the early 18th and late 19th centuries, respectively. In the early 21st century, their use is declining and has been banned in some countries, states and medical institutions. In 2002, the U.S. Senate passed legislation to phase out the sale of non-prescription mercury thermometers. In 2003, Washington and Maine became the first states to ban mercury blood pressure devices.^[54] Mercury compounds are found in some over-the-counter drugs, including topical antiseptics, stimulant laxatives, diaper-rash ointment, eye drops, and nasal sprays. The FDA has «inadequate data to establish general recognition of the safety and effectiveness» of the mercury ingredients in these products.^[55] Mercury is still used in some diuretics although substitutes now exist for most therapeutic uses.

Production of chlorine and caustic soda

Chlorine is produced from sodium chloride (common salt, NaCl) using electrolysis to separate the metallic sodium from the chlorine gas. Usually the salt is dissolved in water to produce a brine. By-products of any such chloralkali process are hydrogen (H₂) and sodium hydroxide (NaOH), which is commonly called caustic soda or lye. By far the largest use of mercury^[56][57] in the late 20th century was in the mercury cell process (also called the Castner-Kellner process) where metallic sodium is formed as an amalgam at a cathode made from mercury; this sodium is then reacted with water to produce sodium hydroxide.^[58] Many of the industrial mercury releases of the 20th century came from this process, although modern plants claimed to be safe in this regard.^[57] After about 1985, all new chloralkali production facilities that were built in the United States used membrane cell or diaphragm cell technologies to produce chlorine.

Laboratory uses

Some medical thermometers, especially those for high temperatures, are filled with mercury; they are gradually disappearing. In the United States, non-prescription sale of mercury fever thermometers has been banned since 2003.^[59]

Some transit telescopes use a basin of mercury to form a flat and absolutely horizontal mirror, useful in determining an absolute vertical or perpendicular reference. Concave horizontal parabolic mirrors may be formed by rotating liquid mercury on a disk, the parabolic form of the liquid thus formed reflecting and focusing incident light. Such liquid-mirror telescopes are cheaper than conventional large mirror telescopes by up to a factor of 100, but the mirror cannot be tilted and always points straight up.^[60][61][62]

Liquid mercury is a part of popular secondary reference electrode (called the calomel electrode) in electrochemistry as an alternative to the standard hydrogen electrode. The calomel electrode is used to work out the electrode potential of half cells.^[63] Last, but not least, the triple point of mercury, −38.8344 °C, is a fixed point used as a temperature standard for the International Temperature Scale (ITS-90).^[6]

In polarography both the dropping mercury electrode^[64] and the hanging mercury drop electrode^[65] use elemental mercury. This use allows a new uncontaminated electrode to be available for each measurement or each new experiment.

Mercury-containing compounds are also of use in the field of structural biology. Mercuric compounds such as mercury(II) chloride or potassium tetraiodomercurate(II) can be added to protein crystals in an effort to create heavy atom derivatives that can be used to solve the phase problem in X-ray crystallography via isomorphous replacement or anomalous scattering methods.

Niche uses

Gaseous mercury is used in mercury-vapor lamps and some «neon sign» type advertising signs and fluorescent lamps. Those low-pressure lamps emit very spectrally narrow lines, which are traditionally used in optical spectroscopy for calibration of spectral position. Commercial calibration lamps are sold for this purpose; reflecting a fluorescent ceiling light into a spectrometer is a common calibration practice.^[66] Gaseous mercury is also found in some electron tubes, including ignitrons, thyratrons, and mercury arc rectifiers.^[67] It is also used in specialist medical care lamps for skin tanning and disinfection.^[68] Gaseous mercury is added to cold cathode argon-filled lamps to increase the ionization and electrical conductivity. An argon-filled lamp without mercury will have dull spots and will fail to light correctly. Lighting containing mercury can be bombarded/oven pumped only once. When added to neon filled tubes the light produced will be inconsistent red/blue spots until the initial burning-in process is completed; eventually it will light a consistent dull off-blue color.^[69]

• 

  The deep violet glow of a mercury vapor discharge in a germicidal lamp, whose spectrum is rich in invisible ultraviolet radiation.

• 

  Skin tanner containing a low-pressure mercury vapor lamp and two infrared lamps, which act both as light source and electrical ballast

• 

  Assorted types of fluorescent lamps.

• 

  The miniaturized Deep Space Atomic Clock is a linear ion-trap-based mercury ion clock, designed for precise and real-time radio navigation in deep space.

The Deep Space Atomic Clock (DSAC) under development by the Jet Propulsion Laboratory utilises mercury in a linear ion-trap-based clock. The novel use of mercury allows very compact atomic clocks, with low energy requirements, and is therefore ideal for space probes and Mars missions.^[70]

Cosmetics

Mercury, as thiomersal, is widely used in the manufacture of mascara. In 2008, Minnesota became the first state in the United States to ban intentionally added mercury in cosmetics, giving it a tougher standard than the federal government.^[71]

A study in geometric mean urine mercury concentration identified a previously unrecognized source of exposure (skin care products) to inorganic mercury among New York City residents. Population-based biomonitoring also showed that mercury concentration levels are higher in consumers of seafood and fish meals.^[72]

Skin whitening

Mercury is effective as an active ingredient in skin whitening compounds used to depigment skin.^[73] The Minamata Convention on Mercury limits the concentration of mercury in such whiteners to 1 part per million. However, as of 2022, many commercially sold whitener products continue to exceed that limit, and are considered toxic.^[74]

Firearms

Mercury(II) fulminate is a primary explosive which is mainly used as a primer of a cartridge in firearms.

Historic uses

Many historic applications made use of the peculiar physical properties of mercury, especially as a dense liquid and a liquid metal:

• Quantities of liquid mercury ranging from 90 to 600 grams (3.2 to 21.2 oz) have been recovered from elite Maya tombs (100–700 AD)^[25] or ritual caches at six sites. This mercury may have been used in bowls as mirrors for divinatory purposes. Five of these date to the Classic Period of Maya civilization (c. 250–900) but one example predated this.^[75]
• In Islamic Spain, it was used for filling decorative pools. Later, the American artist Alexander Calder built a mercury fountain for the Spanish Pavilion at the 1937 World Exhibition in Paris. The fountain is now on display at the Fundació Joan Miró in Barcelona.^[76]
• Mercury was used inside wobbler lures. Its heavy, liquid form made it useful since the lures made an attractive irregular movement when the mercury moved inside the plug. Such use was stopped due to environmental concerns, but illegal preparation of modern fishing plugs has occurred.
• The Fresnel lenses of old lighthouses used to float and rotate in a bath of mercury which acted like a bearing.^[77]
• Mercury sphygmomanometers (blood pressure meter), barometers, diffusion pumps, coulometers, and many other laboratory instruments took advantage of mercury’s properties as a very dense, opaque liquid with a nearly linear thermal expansion.^[78]
• As an electrically conductive liquid, it was used in mercury switches (including home mercury light switches installed prior to 1970), tilt switches used in old fire detectors, and tilt switches in some home thermostats.^[79]
• Owing to its acoustic properties, mercury was used as the propagation medium in delay-line memory devices used in early digital computers of the mid-20th century.
• Experimental mercury vapor turbines were installed to increase the efficiency of fossil-fuel electrical power plants.^[80] The South Meadow power plant in Hartford, CT employed mercury as its working fluid, in a binary configuration with a secondary water circuit, for a number of years starting in the late 1920s in a drive to improve plant efficiency. Several other plants were built, including the Schiller Station in Portsmouth, NH, which went online in 1950. The idea did not catch on industry-wide due to the weight and toxicity of mercury, as well as the advent of supercritical steam plants in later years.^[81][82]
• Similarly, liquid mercury was used as a coolant for some nuclear reactors; however, sodium is proposed for reactors cooled with liquid metal, because the high density of mercury requires much more energy to circulate as coolant.^[83]
• Mercury was a propellant for early ion engines in electric space propulsion systems. Advantages were mercury’s high molecular weight, low ionization energy, low dual-ionization energy, high liquid density and liquid storability at room temperature. Disadvantages were concerns regarding environmental impact associated with ground testing and concerns about eventual cooling and condensation of some of the propellant on the spacecraft in long-duration operations. The first spaceflight to use electric propulsion was a mercury-fueled ion thruster developed at NASA Glenn Research Center and flown on the Space Electric Rocket Test «SERT-1» spacecraft launched by NASA at its Wallops Flight Facility in 1964. The SERT-1 flight was followed up by the SERT-2 flight in 1970. Mercury and caesium were preferred propellants for ion engines until Hughes Research Laboratory performed studies finding xenon gas to be a suitable replacement. Xenon is now the preferred propellant for ion engines as it has a high molecular weight, little or no reactivity due to its noble gas nature, and has a high liquid density under mild cryogenic storage.^[84][85]

Other applications made use of the chemical properties of mercury:

• The mercury battery is a non-rechargeable electrochemical battery, a primary cell, that was common in the middle of the 20th century. It was used in a wide variety of applications and was available in various sizes, particularly button sizes. Its constant voltage output and long shelf life gave it a niche use for camera light meters and hearing aids. The mercury cell was effectively banned in most countries in the 1990s due to concerns about the mercury contaminating landfills.^[86]
• Mercury was used for preserving wood, developing daguerreotypes, silvering mirrors, anti-fouling paints (discontinued in 1990), herbicides (discontinued in 1995), interior latex paint, handheld maze games, cleaning, and road leveling devices in cars. Mercury compounds have been used in antiseptics, laxatives, antidepressants, and in antisyphilitics.
• It was allegedly used by allied spies to sabotage Luftwaffe planes: a mercury paste was applied to bare aluminium, causing the metal to rapidly corrode; this would cause structural failures.^[87]
• Chloralkali process: The largest industrial use of mercury during the 20th century was in electrolysis for separating chlorine and sodium from brine; mercury being the anode of the Castner-Kellner process. The chlorine was used for bleaching paper (hence the location of many of these plants near paper mills) while the sodium was used to make sodium hydroxide for soaps and other cleaning products. This usage has largely been discontinued, replaced with other technologies that utilize membrane cells.^[88]
• As electrodes in some types of electrolysis, batteries (mercury cells), sodium hydroxide and chlorine production, handheld games, catalysts, insecticides.
• Mercury was once used as a gun barrel bore cleaner.^[89][90]
• From the mid-18th to the mid-19th centuries, a process called «carroting» was used in the making of felt hats. Animal skins were rinsed in an orange solution (the term «carroting» arose from this color) of the mercury compound mercuric nitrate, Hg(NO₃)₂·2H₂O.^[91] This process separated the fur from the pelt and matted it together. This solution and the vapors it produced were highly toxic. The United States Public Health Service banned the use of mercury in the felt industry in December 1941. The psychological symptoms associated with mercury poisoning inspired the phrase «mad as a hatter». Lewis Carroll’s «Mad Hatter» in his book Alice’s Adventures in Wonderland was a play on words based on the older phrase, but the character himself does not exhibit symptoms of mercury poisoning.^[92]
• Gold and silver mining. Historically, mercury was used extensively in hydraulic gold mining in order to help the gold to sink through the flowing water-gravel mixture. Thin gold particles may form mercury-gold amalgam and therefore increase the gold recovery rates.^[6] Large-scale use of mercury stopped in the 1960s. However, mercury is still used in small scale, often clandestine, gold prospecting. It is estimated that 45,000 metric tons of mercury used in California for placer mining have not been recovered.^[93] Mercury was also used in silver mining.^[94]

Historic medicinal uses

Mercury(I) chloride (also known as calomel or mercurous chloride) has been used in traditional medicine as a diuretic, topical disinfectant, and laxative. Mercury(II) chloride (also known as mercuric chloride or corrosive sublimate) was once used to treat syphilis (along with other mercury compounds), although it is so toxic that sometimes the symptoms of its toxicity were confused with those of the syphilis it was believed to treat.^[95] It is also used as a disinfectant. Blue mass, a pill or syrup in which mercury is the main ingredient, was prescribed throughout the 19th century for numerous conditions including constipation, depression, child-bearing and toothaches.^[96] In the early 20th century, mercury was administered to children yearly as a laxative and dewormer, and it was used in teething powders for infants. The mercury-containing organohalide merbromin (sometimes sold as Mercurochrome) is still widely used but has been banned in some countries such as the U.S.^[97]

Toxicity and safety

Mercury

Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H330, H360D, H372, H410
Precautionary statements	P201, P233, P260, P273, P280, P304, P308, P310, P313, P340, P391, P403[98]
NFPA 704 (fire diamond)	2 0 0

Mercury and most of its compounds are extremely toxic and must be handled with care; in cases of spills involving mercury (such as from certain thermometers or fluorescent light bulbs), specific cleaning procedures are used to avoid exposure and contain the spill.^[99] Protocols call for physically merging smaller droplets on hard surfaces, combining them into a single larger pool for easier removal with an eyedropper, or for gently pushing the spill into a disposable container. Vacuum cleaners and brooms cause greater dispersal of the mercury and should not be used. Afterwards, fine sulfur, zinc, or some other powder that readily forms an amalgam (alloy) with mercury at ordinary temperatures is sprinkled over the area before itself being collected and properly disposed of. Cleaning porous surfaces and clothing is not effective at removing all traces of mercury and it is therefore advised to discard these kinds of items should they be exposed to a mercury spill.

Mercury can be absorbed through the skin and mucous membranes and mercury vapors can be inhaled, so containers of mercury are securely sealed to avoid spills and evaporation. Heating of mercury, or of compounds of mercury that may decompose when heated, should be carried out with adequate ventilation in order to minimize exposure to mercury vapor. The most toxic forms of mercury are its organic compounds, such as dimethylmercury and methylmercury. Mercury can cause both chronic and acute poisoning.

Releases in the environment

Preindustrial deposition rates of mercury from the atmosphere may be about 4 ng /(1 L of ice deposit). Although that can be considered a natural level of exposure, regional or global sources have significant effects. Volcanic eruptions can increase the atmospheric source by 4–6 times.^[100]

Natural sources, such as volcanoes, are responsible for approximately half of atmospheric mercury emissions. The human-generated half can be divided into the following estimated percentages:^{[101][102][103]}

• 65% from stationary combustion, of which coal-fired power plants are the largest aggregate source (40% of U.S. mercury emissions in 1999). This includes power plants fueled with gas where the mercury has not been removed. Emissions from coal combustion are between one and two orders of magnitude higher than emissions from oil combustion, depending on the country.^[101]
• 11% from gold production. The three largest point sources for mercury emissions in the U.S. are the three largest gold mines. Hydrogeochemical release of mercury from gold-mine tailings has been accounted as a significant source of atmospheric mercury in eastern Canada.^[104]
• 6.8% from non-ferrous metal production, typically smelters.
• 6.4% from cement production.
• 3.0% from waste disposal, including municipal and hazardous waste, crematoria, and sewage sludge incineration.
• 3.0% from caustic soda production.
• 1.4% from pig iron and steel production.
• 1.1% from mercury production, mainly for batteries.
• 2.0% from other sources.

The above percentages are estimates of the global human-caused mercury emissions in 2000, excluding biomass burning, an important source in some regions.^[101]

Recent atmospheric mercury contamination in outdoor urban air was measured at 0.01–0.02 μg/m³. A 2001 study measured mercury levels in 12 indoor sites chosen to represent a cross-section of building types, locations and ages in the New York area. This study found mercury concentrations significantly elevated over outdoor concentrations, at a range of 0.0065 – 0.523 μg/m³. The average was 0.069 μg/m³.^[105]

Artificial lakes, or reservoirs, may be contaminated with mercury due to the absorption by the water of mercury from submerged trees and soil.
For example, Williston Lake in northern British Columbia, created by the damming of the Peace River in 1968, is still sufficiently contaminated with mercury that it is inadvisable to consume fish from the lake.^[106][107] Permafrost soils have accumulated mercury through atmospheric deposition,^[108] and permafrost thaw in cryospheric regions is also a mechanism of mercury release into lakes, rivers, and wetlands.^[109][110]

Mercury also enters into the environment through the improper disposal (e.g., land filling, incineration) of certain products. Products containing mercury include: auto parts, batteries, fluorescent bulbs, medical products, thermometers, and thermostats.^[111] Due to health concerns (see below), toxics use reduction efforts are cutting back or eliminating mercury in such products. For example, the amount of mercury sold in thermostats in the United States decreased from 14.5 tons in 2004 to 3.9 tons in 2007.^[112]

Most thermometers now use pigmented alcohol instead of mercury. Mercury thermometers are still occasionally used in the medical field because they are more accurate than alcohol thermometers, though both are commonly being replaced by electronic thermometers and less commonly by galinstan thermometers. Mercury thermometers are still widely used for certain scientific applications because of their greater accuracy and working range.

Historically, one of the largest releases was from the Colex plant, a lithium isotope separation plant at Oak Ridge, Tennessee. The plant operated in the 1950s and 1960s. Records are incomplete and unclear, but government commissions have estimated that some two million pounds of mercury are unaccounted for.^[113]

A serious industrial disaster was the dumping of waste mercury compounds into Minamata Bay, Japan, between 1932 and 1968. It is estimated that over 3,000 people suffered various deformities, severe mercury poisoning symptoms or death from what became known as Minamata disease.^[114][115]

The tobacco plant readily absorbs and accumulates heavy metals such as mercury from the surrounding soil into its leaves. These are subsequently inhaled during tobacco smoking.^[116] While mercury is a constituent of tobacco smoke,^[117] studies have largely failed to discover a significant correlation between smoking and Hg uptake by humans compared to sources such as occupational exposure, fish consumption, and amalgam tooth fillings.^[118]

Sediment contamination

Sediments within large urban-industrial estuaries act as an important sink for point source and diffuse mercury pollution within catchments.^[119] A 2015 study of foreshore sediments from the Thames estuary measured total mercury at 0.01 to 12.07 mg/kg with mean of 2.10 mg/kg and median of 0.85 mg/kg (n=351).^[119] The highest mercury concentrations were shown to occur in and around the city of London in association with fine grain muds and high total organic carbon content.^[119] The strong affinity of mercury for carbon rich sediments has also been observed in salt marsh sediments of the River Mersey mean of 2 mg/kg up to 5 mg/kg.^[120] These concentrations are far higher than those shown in salt marsh river creek sediments of New Jersey and mangroves of Southern China which exhibit low mercury concentrations of about 0.2 mg/kg.^[121][122]

Occupational exposure

Due to the health effects of mercury exposure, industrial and commercial uses are regulated in many countries. The World Health Organization, OSHA, and NIOSH all treat mercury as an occupational hazard, and have established specific occupational exposure limits. Environmental releases and disposal of mercury are regulated in the U.S. primarily by the United States Environmental Protection Agency.

Fish

Fish and shellfish have a natural tendency to concentrate mercury in their bodies, often in the form of methylmercury, a highly toxic organic compound of mercury. Species of fish that are high on the food chain, such as shark, swordfish, king mackerel, bluefin tuna, albacore tuna, and tilefish contain higher concentrations of mercury than others. Because mercury and methylmercury are fat soluble, they primarily accumulate in the viscera, although they are also found throughout the muscle tissue.^[123] Mercury presence in fish muscles can be studied using non-lethal muscle biopsies.^[124] Mercury present in prey fish accumulates in the predator that consumes them. Since fish are less efficient at depurating than accumulating methylmercury, methylmercury concentrations in the fish tissue increase over time. Thus species that are high on the food chain amass body burdens of mercury that can be ten times higher than the species they consume. This process is called biomagnification. Mercury poisoning happened this way in Minamata, Japan, now called Minamata disease.

Cosmetics

Some facial creams contain dangerous levels of mercury. Most contain comparatively non-toxic inorganic mercury, but products containing highly toxic organic mercury have been encountered.^[125][126]

Effects and symptoms of mercury poisoning

Toxic effects include damage to the brain, kidneys and lungs. Mercury poisoning can result in several diseases, including acrodynia (pink disease), Hunter-Russell syndrome, and Minamata disease.

Symptoms typically include sensory impairment (vision, hearing, speech), disturbed sensation and a lack of coordination. The type and degree of symptoms exhibited depend upon the individual toxin, the dose, and the method and duration of exposure. Case–control studies have shown effects such as tremors, impaired cognitive skills, and sleep disturbance in workers with chronic exposure to mercury vapor even at low concentrations in the range 0.7–42 μg/m³.^[127][128] A study has shown that acute exposure (4–8 hours) to calculated elemental mercury levels of 1.1 to 44 mg/m³ resulted in chest pain, dyspnea, cough, hemoptysis, impairment of pulmonary function, and evidence of interstitial pneumonitis.^[129] Acute exposure to mercury vapor has been shown to result in profound central nervous system effects, including psychotic reactions characterized by delirium, hallucinations, and suicidal tendency. Occupational exposure has resulted in broad-ranging functional disturbance, including erethism, irritability, excitability, excessive shyness, and insomnia. With continuing exposure, a fine tremor develops and may escalate to violent muscular spasms. Tremor initially involves the hands and later spreads to the eyelids, lips, and tongue. Long-term, low-level exposure has been associated with more subtle symptoms of erethism, including fatigue, irritability, loss of memory, vivid dreams and depression.^[130][131]

Treatment

Research on the treatment of mercury poisoning is limited. Currently available drugs for acute mercurial poisoning include chelators N-acetyl-D, L-penicillamine (NAP), British Anti-Lewisite (BAL), 2,3-dimercapto-1-propanesulfonic acid (DMPS), and dimercaptosuccinic acid (DMSA). In one small study including 11 construction workers exposed to elemental mercury, patients were treated with DMSA and NAP.^[132] Chelation therapy with both drugs resulted in the mobilization of a small fraction of the total estimated body mercury. DMSA was able to increase the excretion of mercury to a greater extent than NAP.^[133]

Regulations

International

140 countries agreed in the Minamata Convention on Mercury by the United Nations Environment Programme (UNEP) to prevent emissions.^[134] The convention was signed on 10 October 2013.^[135]

United States

In the United States, the Environmental Protection Agency is charged with regulating and managing mercury contamination. Several laws give the EPA this authority, including the Clean Air Act, the Clean Water Act, the Resource Conservation and Recovery Act, and the Safe Drinking Water Act. Additionally, the Mercury-Containing and Rechargeable Battery Management Act, passed in 1996, phases out the use of mercury in batteries, and provides for the efficient and cost-effective disposal of many types of used batteries.^[136] North America contributed approximately 11% of the total global anthropogenic mercury emissions in 1995.^[137]

The United States Clean Air Act, passed in 1990, put mercury on a list of toxic pollutants that need to be controlled to the greatest possible extent. Thus, industries that release high concentrations of mercury into the environment agreed to install maximum achievable control technologies (MACT). In March 2005, the EPA promulgated a regulation^[138] that added power plants to the list of sources that should be controlled and instituted a national cap and trade system. States were given until November 2006 to impose stricter controls, but after a legal challenge from several states, the regulations were struck down by a federal appeals court on 8 February 2008. The rule was deemed not sufficient to protect the health of persons living near coal-fired power plants, given the negative effects documented in the EPA Study Report to Congress of 1998.^[139] However newer data published in 2015 showed that after introduction of the stricter controls mercury declined sharply, indicating that the Clean Air Act had its intended impact.^[140]

The EPA announced new rules for coal-fired power plants on 22 December 2011.^[141] Cement kilns that burn hazardous waste are held to a looser standard than are standard hazardous waste incinerators in the United States, and as a result are a disproportionate source of mercury pollution.^[142]

European Union

In the European Union, the directive on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment (see RoHS) bans mercury from certain electrical and electronic products, and limits the amount of mercury in other products to less than 1000 ppm.^[143] There are restrictions for mercury concentration in packaging (the limit is 100 ppm for sum of mercury, lead, hexavalent chromium and cadmium) and batteries (the limit is 5 ppm).^[144] In July 2007, the European Union also banned mercury in non-electrical measuring devices, such as thermometers and barometers. The ban applies to new devices only, and contains exemptions for the health care sector and a two-year grace period for manufacturers of barometers.^[145]

Norway

Norway enacted a total ban on the use of mercury in the manufacturing and import/export of mercury products, effective 1 January 2008.^[146] In 2002, several lakes in Norway were found to have a poor state of mercury pollution, with an excess of 1 μg/g of mercury in their sediment.^[147]
In 2008, Norway’s Minister of Environment Development Erik Solheim said: «Mercury is among the most dangerous environmental toxins. Satisfactory alternatives to Hg in products are
available, and it is therefore fitting to induce a ban.»^[148]

Sweden

Products containing mercury were banned in Sweden in 2009.^[149][150]

Denmark

In 2008, Denmark also banned dental mercury amalgam,^[148] except for molar masticating surface fillings in permanent (adult) teeth.

See also

• Mercury pollution in the ocean
• Red mercury
• COLEX process (isotopic separation)

References

Further reading

• Johnston, Andrew Scott (15 September 2013). Mercury and the Making of California: Mining, Landscape, and Race, 1840–1890. TotalBoox, TBX. University Press of Colorado. ISBN 9781457183997. OCLC 969039240.

External links

• Chemistry in its element podcast (MP3) from the Royal Society of Chemistry’s Chemistry World: Mercury
• Mercury at The Periodic Table of Videos (University of Nottingham)
• Centers for Disease Control and Prevention – Mercury Topic
• EPA fish consumption guidelines
• Hg 80 Mercury
• Material Safety Data Sheet – Mercury
• Stopping Pollution: Mercury – Oceana
• Natural Resources Defense Council (NRDC): Mercury Contamination in Fish guide – NRDC
• NLM Hazardous Substances Databank – Mercury
• BBC – Earth News – Mercury «turns» wetland birds such as ibises homosexual
• Changing Patterns in the Use, Recycling, and Material Substitution of Mercury in the United States United States Geological Survey
• Thermodynamical data on liquid mercury.
• «Mercury (element)» . Encyclopædia Britannica (11th ed.). 1911.

Оглавление

1. 1 Введение
2. 2 История
3. 3 Химические свойства
4. 4 Физические свойства
5. 5 Получение
6. 6 Нахождение в природе
7. 7 Применение ртути и её соединений
   1. 7.1 Медицина
   2. 7.2 Техника
   3. 7.3 Металлургия
   4. 7.4 Химическая промышленность
   5. 7.5 Сельское хозяйство
8. 8 Заключение
   1. 8.1 Запрет использования ртутьсодержащей продукции
   2. 8.2 Демеркуризация
   3. 8.3 Гигиеническое нормирование концентраций ртути
9. 9 Список источников

Введение

Ртуть (Hg, от лат. Hydrargyrum) – элемент шестого периода
периодической системы химических элементов Д. И. Менделеева с атомным номером
80, относящийся к подгруппе цинка (побочной подгруппе II группы). Простое вещество ртуть –
переходный металл, при комнатной температуре представляющий собой тяжёлую
серебристо-белую жидкость, пары которой чрезвычайно ядовиты. Ртуть – один из
двух химических элементов (и единственный металл), простые вещества которых при
нормальных условиях находятся в жидком агрегатном состоянии (второй такой
элемент – бром).

История

Ртуть известна с древних времен. Нередко её находили в самородном
виде (жидкие капли на горных породах), но чаще получали обжигом природной
киновари. Древние греки и римляне использовали ртуть для очистки золота
(амальгамирование), знали о токсичности самой ртути и её соединений, в частности
сулемы. Много веков алхимики считали ртуть главной составной частью всех
металлов и полагали, что если жидкой ртути возвратить твердость при помощи серы
или мышьяка, то получится золото. Выделение ртути в чистом виде было описано
шведским химиком Георгом Брандтом в 1735 г. Для представления элемента как у
алхимиков, так и в нынешнее время используется символ планеты Меркурий. Но
принадлежность ртути к металлам была доказана только трудами Ломоносова и
Брауна, которые в декабре 1759 года смогли заморозить ртуть и установить её
металлические свойства: ковкость, электропроводность и др.

Ртуть – вещество первого класса опасности. Является переходным металлом,
представляющим собой серебристо-белую жидкость с тяжелой массой, пары которой
очень ядовиты (в условиях привычной температуры жилых помещений).

Ртуть Hg,
химический элемент II
группы периодичной системы, атомное число 80, атомная масса 200,59. Природная
ртуть состоит из семи стабильных изотопов: 196Hg (0,146%), 198Hg (10,02%), 199Hg (16,84%), 200Hg (23,13%), 201Hg (13,22%), 202Hg (29,80%), 204Hg (6,85%). Поперечное сечение захвата
тепловых нейтронов для природной смеси изотопов 38·10-27м2. Конфигурация
внешних электронных оболочек атома 5s25p65d106s2; степень окисления + 1 и + 2; энергии
ионизации Hg0:Hg+:Hg2+:Hg3+ соответственно 10,4376, 18,756 и 34,2 эВ;
сродство к электрону – 0,19 эВ; работа выхода электрона 4,52 эВ; электроотрицательность
по Полингу 1,9; атомный радиус 0,155 нм, ковалентный радиус 0,149 нм, ионный
радиус (в скобках указано координационное число) Hg+ 0,111 нм (3), 0,133 нм (6), Hg2+ 0,083 нм (2), 0,110 нм (4), 0,116 нм (6),
0,128нм (8).

Химические свойства

Для ртути характерны две степени
окисления: +1 и +2. В степени окисления +1 ртуть представляет собой
двухъядерный катион Hg22+ со
связью металл-металл. Ртуть – один из немногих металлов, способных формировать
такие катионы, и у ртути они – самые устойчивые.

В степени окисления +1 ртуть склонна к диспропорционированию.
Оно протекает при нагревании и подщелачивании.

добавлении лигандов, стабилизирующих степень окисления ртути +2.

Из-за диспропорционирования и гидролиза гидроксид ртути (I) получить не удаётся.

На холоде ртуть +2
и металлическая ртуть, наоборот, сопропорционируют. Поэтому, в частности, при
реакции нитрата ртути (II) со ртутью получается нитрат ртути (I).

В степени окисления +2 ртуть образует катионы Hg²⁺, которые очень легко
гидролизуются. При этом гидроксид ртути Hg(OH)₂
существует только в очень разбавленных (<10⁻⁴моль/л) растворах. В
более концентрированных растворах он дегидратируется

В очень концентрированной щелочи оксид ртути частично растворяется с
образованием гидроксокомплекса

Ртуть в степени окисления +2 образует уникально прочные комплексы со
многими лигандами, причём как жёсткими, так и мягкими по теории ЖМКО. С йодом
(-1), серой (-2) и углеродом она образует очень прочные ковалентные связи. По
устойчивости связей металл-углерод ртути нет равных среди других металлов,
поэтому получено огромное количество ртутьорганических соединений.

Из элементов IIБ
группы именно у ртути появляется возможность разрушения очень устойчивой 6d¹⁰ – электронной
оболочки, что приводит к возможности существования соединений ртути(IV), но они крайне
малоустойчивы, поэтому эту степень окисления скорее можно отнести к курьёзной,
чем к характерной. В частности, при взаимодействии атомов ртути и смеси неона и
фтора при температуре 4К получен HgF_4.

Физические свойства

Ртуть – единственный металл, который находится в жидком состоянии при комнатной температуре. Температура плавления составляет 234,32 K (-38,83 °C),кипит при 629,88 K (356,73 °C), критическая точка –1750 K (1477 °C), 152 МПа (1500 атм). Обладает свойствами диамагнетика. Образует со многими металлами жидкие и твёрдые сплавы – амальгамы. Стойкие к амальгамированию металлы: V, Fe, Mo, Cs, Nb, Ta, W, Co .

Плотность ртути при
нормальных условиях – 13 500 кг/м3.

Таблица
1 – Зависимость плотности от температуры

Температура в °С	ρ, 103 кг/м3	Температура в °С	ρ, 103 кг/м3
0	13,5951	50	13,4723
5	13,5827	55	13,4601
10	13,5704	60	13,4480
15	13,5580	65	13,4358
20	13,5457	70	13,4237
25	13,5335	75	13,4116
30	13,5212	80	13,3995
35	13,5090	90	13,3753
40	13,4967	100	13,3514
45	13,4845	300	12,875

Простое вещество ртуть (CAS-номер: 7439-97-6) – переходный металл, при комнатной
температуре представляет собой тяжёлую серебристо-белую жидкость, пары которой
чрезвычайно ядовиты. Ртуть – один из двух химических элементов (и единственный
металл), простые вещества которых при нормальных условиях находятся в жидком
агрегатном состоянии (второй элемент – бром).

Получение

Ртуть
получают путём восстановления из её наиболее распространённого минерала –
киновари.

Пары ртути конденсируют и собирают. Этот способ применяли ещё алхимики
древности.

На протяжении многих столетий в Европе основным и единственным
месторождением ртути был Альмаден в Испании. В Новое время с ним стала
конкурировать Идрия вовладениях Габсбургов (современная Словения). Там же
появилась первая лечебница для поражённых отравлением парами ртути рудокопов. В
2012 г. ЮНЕСКО объявило промышленную инфраструктуру Альмдена и Идрии памятником
Всемирного наследия человечества.

В надписях во дворце древнеперсидских царей Ахеменидов (VI–IV века до н. э.) в Сузах упоминается,
что ртутную киноварь доставляли сюда с Зеравшанских гор и использовали в
качестве краски.

Нахождение в природе

Ртуть – относительно редкий элемент в земной коре со средней концентрацией
83 мг/т. Однако ввиду того, что ртуть слабо связывается химически с наиболее
распространёнными в земной коре элементами, ртутные руды могут быть очень
концентрированными по сравнению с обычными породами. Наиболее богатые ртутью
руды содержат до 2,5 % ртути. Основная форма нахождения ртути в природе – рассеянная,
и только 0,02 % её заключено в месторождениях. Содержание ртути в различных
типах изверженных пород близки между собой (около 100 мг/т). Из осадочных пород
максимальные концентрации ртути установлены в глинистых сланцах (до 200 мг/т).
В водах Мирового океана содержание ртути – 0,1 мкг/л. Важнейшей геохимической
особенностью ртути является то, что среди других халькофильных элементов она
обладает самым высоким потенциалом ионизации. Это определяет такие свойства
ртути, как способность восстанавливаться до атомарной формы (самородной ртути),
значительную химическую стойкость к кислороду и кислотам.

Ртуть присутствует в большинстве сульфидных минералов. Особенно
высокие её содержания (до тысячных и сотых долей процента) устанавливаются в
блёклых рудах, антимонитах, сфалеритах и реальгарах. Близость ионных радиусов
двухвалентной ртути и кальция, одновалентной ртути и бария определяет их
изоморфизм во флюоритах и баритах. В киновари и метациннабарите сера иногда
замещается селеном или теллуром; содержание селена часто составляет сотые и
десятые доли процента. Известны крайне редкие селениды ртути – тиманит (HgSe) и онофрит (смесь
тиманита и сфалерита).

Ртуть является одним из наиболее чувствительных индикаторов скрытого
оруденения не только ртутных, но и различных сульфидных месторождений, поэтому
ореолы ртути обычно выявляются над всеми скрытыми сульфидными залежами и вдоль
дорудных разрывных нарушений. Эта особенность, а также незначительное
содержание ртути в породах, объясняются высокой упругостью паров ртути,
возрастающей с увеличением температуры и определяющей высокую миграцию этого
элемента в газовой фазе.

В поверхностных условиях киноварь и металлическая ртуть не растворимы
в воде, но при их наличии (Fe₂(SO₄)₃,
озон, пероксид водорода) растворимость этих минералов достигает десятков мг/л.
Особенно хорошо растворяется ртуть в сульфидах едких щелочей с образованием,
например, комплекса HgS•nNa₂S. Ртуть легко сорбируется
глинами, гидроокислами железа и марганца, глинистыми сланцами и углями.

В природе известно около 20 минералов ртути, но главное промышленное
значение имеет киноварь HgS
(86,2 % Hg). В редких
случаях предметом добычи является самородная ртуть, метациннабарит HgS и блёклая руда – шватцит
(до 17 % Hg). На
единственном месторождении Гуитцуко (Мексика) главным рудным минералом является
ливингстонит HgSb₄S₇. В зоне
окисления ртутных месторождений образуются вторичные минералы ртути. К ним относятся,
прежде всего, самородная ртуть, реже метациннабарит, отличающиеся от таких же
первичных минералов большей чистотой состава. Относительно распространена
каломель Hg₂Cl₂. На
месторождении Терлингуа (Техас) распространены и другие гипергенные галоидные
соединения – терлингуаит Hg₂ClO, эглестонит Hg₄Cl.

Применение ртути и её соединений

Медицина

В связи с высокой токсичностью ртуть почти полностью вытеснена из
медицинских препаратов. Её соединения (в частности, мертиолят) иногда используются
в малых количествах как консервант для вакцин. Сама ртуть сохраняется в ртутных
медицинских термометрах (один медицинский термометр содержит до 2 г ртути).

Однако вплоть до
1970-х годов соединения ртути использовались в медицине очень активно:

●     
хлорид ртути (I) (каломель) – слабительное;

●     
меркузал и промеран – сильные
мочегонные;

●     
хлорид ртути (II), цианид ртути (II), амидохлорид ртути и жёлтый оксид
ртути(II) –
антисептики (в том числе в составе мазей).

Известны случаи, когда при завороте кишок больному вливали в желудок
стакан ртути. По мнению древних врачевателей, предлагавших такой метод лечения,
ртуть благодаря своей тяжести и подвижности должна была пройти по кишечнику и
под своим весом расправить его перекрутившиеся части.

Амальгаму серебра применяли в стоматологии в качестве материала
зубных пломб до появления светоотверждаемых материалов.

Ртуть-203 (T_1/2 = 53
сек) используется в радиофармакологии.

Техника

●     
Ртуть используется как рабочее тело
в ртутных термометрах (особенно высокоточных), так как (а) обладает довольно
широким диапазоном, в котором находится в жидком состоянии, (б) её коэффициент
термического расширения почти не зависит от температуры и (в) обладает
сравнительно малой теплоёмкостью. Сплав ртути с таллием используется для
низкотемпературных термометров.

●     
Парами ртути заполняют
люминесцентные лампы, поскольку пары светятся в тлеющем разряде. В спектре
испускания паров ртути много ультрафиолетового света и, чтобы преобразовать его
в видимый, стекло люминесцентных ламп изнутри покрывают люминофором. Без люминофора
ртутные лампы являются источником жесткого ультрафиолета (254 нм), в каковом
качестве и используются. Такие лампы делают из кварцевого стекла, пропускающего
ультрафиолет, поэтому они называются кварцевыми.

●     
Ртутные электрические вентили
(игнитроны) в мощных выпрямительных устройствах, электроприводах,
электросварочных устройствах, тяговых и выпрямительных подстанциях и т. п.^[18] со
средней силой тока в сотни ампер и выпрямленным напряжением до 5 кВ.

●     
Ртуть и сплавы на её основе
используются в герметичных выключателях, включающихся при определённом
положении.

●     
Ртуть используется в датчиках положения.

●     
В некоторых химических источниках
тока (например, ртутно-цинковых), в эталонных источниках напряжения (Нормальный
элемент Вестона).

●     
Ртуть также иногда применяется в
качестве рабочего тела в тяжелонагруженных гидродинамических подшипниках.

●     
Ртуть ранее входила в состав
некоторых биоцидных красок для предотвращения обрастания корпуса судов в
морской воде. Сейчас запрещается использовать такого типа покрытия.

●     
Иодид ртути(I) используется как полупроводниковый
детектор радиоактивного излучения.

●     
Фульминат ртути(II) («гремучая ртуть») издавна
применяется в качестве инициирующего ВВ (Детонаторы).

●     
Бромид ртути(I) применяется при термохимическом
разложении воды на водород и кислород (атомно-водородная энергетика).

●     
Перспективно использование ртути в
сплавах с цезием в качестве высокоэффективного рабочего тела в ионных
двигателях.

●     
До середины 20 века ртуть широко
применялась в барометрах и манометрах.

●     
Ртутные вакуумные насосы были
основными источниками вакуума в 19 и начале 20 веков.

●     
Ранее ртуть использовали для
золочения поверхностей методом амальгамирования, однако в настоящее время от
этого метода отказались из-за токсичности ртути.

●     
Соединения ртути использовались в
шляпном производстве для выделки фетра.

Металлургия

●     
Металлическая ртуть применяется для
получения целого ряда важнейших сплавов.

●     
Ранее различные амальгамы металлов,
особенно золота и серебра, широко использовались в ювелирном деле, в
производстве зеркал.

●     
Металлическая ртуть служит катодом
для электролитического получения ряда активных металлов, хлора и щелочей. Сейчас
вместо ртутных катодов используют электролиз с диафрагмой.

●     
Ртуть используется для переработки
вторичного алюминия (см. амальгамация)

●     
Ртуть хорошо смачивает золото,
поэтому ей обрабатывают золотоносные глины для выделения из них этого металла. Эта
технология распространена, в частности, в Амазонии.

Химическая
промышленность

●     
Соли ртути использовали в качестве
катализатора промышленного получения ацетальдегида из ацетилена (реакция
Кучерова), однако в настоящее время ацетальдегид получают прямым каталитическим
окислением этана или этена.

●     
Реактив Несслера используется для
количественного определения аммиака.

Сельское хозяйство

Высокотоксичные соединения ртути – каломель, сулему, мертиолят и
другие – используют для протравливания семенного зерна и в качестве пестицидов.

Заключение

Запрет использования ртутьсодержащей продукции

С 2020 года международная
конвенция, названная в честь массового отравления ртутью и подписанная многими
странами, запретит производство, экспорт и импорт нескольких различных видов
ртутьсодержащих продукции применяемой в быту, в том числе электрических
батарей, электрических выключателей и реле, некоторых видов компактных
люминесцентных ламп (КЛЛ), люминесцентных ламп с холодным катодом или с внешним
электродом, ртутных термометров и приборов измерения давлении. Конвенция вводит
регулирование использования ртути и ограничивает ряд промышленных процессов и
отраслей, в том числе горнодобывающую (особенно непромышленную добычу золота),
производство цемента.

Демеркуризация

Очистка помещений и предметов от загрязнений металлической
ртутью и источников ртутных паров называется демеркуризацией. В быту широко
применяется демеркуризация с помощью серы и хлорного железа FeCl3.

Гигиеническое нормирование концентраций ртути

Предельно допустимые уровни загрязнённости металлической ртутью
и её парами:

●     
ПДК в населённых пунктах
(среднесуточная) – 0,0003 мг/м³

●     
ПДК в жилых помещениях
(среднесуточная) – 0,0003 мг/м³

●     
ПДК воздуха в рабочей зоне (макс.
разовая) – 0,01 мг/м³

●     
ПДК воздуха в рабочей зоне
(среднесменная) – 0,005 мг/м³

●     
ПДК сточных вод (для неорганических
соединений в пересчёте на двухвалентную ртуть) – 0,005 мг/л

●     
ПДК водных объектов
хозяйственно-питьевого и культурного водопользования, в воде водоёмов – 0,0005
мг/л

●     
ПДК морских водоёмов – 0,0001 мг/л

Список источников

1.          
Ртуть  //Материал из Википедии – свободной энциклопедии. 

2.          
Ртуть  // химик. 

3.          
Ртуть  //Глоссарий. Химия. 

  100 граммовая гирька, не тонет в металлическая ртути, из-за разницы по плотности

В природе существует множество полезных ископаемых, которые обладают определёнными характеристиками и используются для различных нужд человека.

Одним из древних металлов является ртуть. Химический элемент имеет особенности, которые делают его незаменимым в современной промышленности.

История открытия

О ртути люди узнали ещё в древние времена. Вещество часто находили в виде самородка, который представлял жидкие капли на горных породах. Но чаще металл получали из его соединения с серой — сульфида ртути (HgS), или киновари. Люди из Древнего Рима и Греции применяли вещество для очистки золота от разных примесей. В то время народы уже раскрыли, что металл и его соединения вредны для здоровья.

О веществе стало известно так рано, потому что добываемая киноварь быстро разлагалась под воздействием высоких температур воздуха и образовывала металлическую ртуть. В период древних цивилизаций люди обжигали киноварь в глиняных сосудах, на крышках которых конденсировался необходимый металл. Сегодня для этого применяют трубчатые печи.

Когда алхимики открыли новый элемент, они назвали его «живым серебром» (argentum vivum). Учёные считали его женским началом веществ и матерью всех металлов. Они полагали, что при помощи мышьяка и серы жидкой ртути можно вернуть твёрдость и получить таким образом золото.

В течение многих столетий алхимики утверждали, что это вещество содержится в любом металле. Кроме того, они верили, что оно могло стать основой для философского камня. Позже веществу дали другое название — hydrargyrum, что с латинского переводится как «жидкое серебро».

В Средневековье известные химические элементы ассоциировали с открытыми в то время семью планетами. Ртуть совпадала с обозначением Меркурия. Так люди подчёркивали близость металла к золоту (Солнцу), поскольку небесное тело расположено близко к светилу. Также название «Mercury» соответствовало уникальному свойству элемента. Капли вещества стремительно перекатывались по гладким поверхностям, что напоминало быстрое передвижение античного бога-посланника Меркурия.

В 1735 году шведский учёный Георг Брандт подробно описал образование вещества в чистом виде. Для обозначения уже использовался символ планеты Меркурий.

В 1759 году Браун и Ломоносов доказали, что вещество относится к металлам. Они смогли определить его металлические свойства в твёрдом агрегатном состоянии после замерзания.

Нахождение в природе

В России есть 23 места, где добывают ртуть. Самое крупное из них находится на Чукотке.

Металл также добывают и в других странах:

• Италия;
• Испания;
• Словения;
• Таджикистан;
• Украина;
• Киргизия.

Концентрация вещества в земной коре составляет всего 83 мг/т. Редкий металл слабо соединяется химически с иными элементами. Но ртутные руды часто бывают очень концентрированными, если их сравнивать с обычными горными породами, и могут содержать до 2,5% серебристого металла.

В основном ртуть рассеяна в природе. Лишь 0,02% от всего её объёма заключено в месторождениях. Наибольшие концентрации наблюдаются в глинистых сланцах. В Мировом океане объём вещества достигает 0,1 мкг/л.

Металл можно обнаружить во многих сульфидных минералах.

Основными природными материалами для добычи вещества выступают антимониты, блёклые руды, сфалериты и реальгары. Ртуть добывают из киновари, метациннабарита, а также из селенидов металла (тиманита и онофрита).

Описание элемента

Элемент расположен между золотом и таллием в таблице Менделеева. Ртуть имеет порядковый номер 80 и обозначается Hg. Она относится к элементам шестого периода и входит в подгруппу цинка. Это единственный металл, простые вещества которого находятся в жидком состоянии при нормальных условиях.

Электронная формула ртути — 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶4d¹⁰4f¹⁴5s²5p⁶5d¹⁰6s². Атомы вещества в соединениях с другими элементами проявляют валентность I и II.

Непрозрачный металл представлен тяжёлой серебристой жидкостью.

Основные физические свойства ртути:

• температура плавления: -38,8°C;
• температура кипения: +356,7°C;
• молярный объём — 14,80 см³/моль;
• атомная масса — 200,6;
• плотность — 13,5 г/см³.

В жидком виде ртуть обладает металлическим блеском. Когда вещество затвердевает, оно приобретает кристаллическое состояние. Ртуть может взаимодействовать со многими металлами, образуя при реакции с ними соединения, которые называются амальгамы. Химический элемент относится к группе диамагнетиков: он не магнитится, а отталкивается в присутствии магнитов. При горении вещество образует ядовитые испарения.

Ртуть характеризуется высоким потенциалом ионизации. Она способна восстанавливаться до атомарной формы (самородка). Кроме того, элемент обладает высокой химической стойкостью к кислороду и кислотам.

Химические особенности

Металл характеризуется степенью окисления +1 и +2. В первом случае он представлен двухъядерным катионом Hg22+ с металлической связью и склонен к диспропорционированию, которое проходит при нагревании и разбавлении водой.

На холоде вещество со степенью окисления +2 и металлическая ртуть сопропорционируют. Реагируя с нитратом металла, элемент образует нитрат ртути. При степени окисления +2 получаются катионы Hg²⁺, которые легко гидролизуются. Гидроксид металла существует лишь в разбавленных растворах, а в жидкостях с высокой концентрацией он дегидратируется.

Элемент со степенью окисления +2 образует с различными лигандами устойчивые комплексы. Прочные ковалентные связи наблюдаются с йодом, серой и углеродом. С последним веществом ртуть образует самые устойчивые соединения.

Сферы использования

Применение ртути в современной промышленности соблюдается с большой осторожностью. Перед работой с этим элементом нужно познакомиться с мерами безопасности.

Сферы использования металла:

• Материал применяется в виде рабочего тела в ртутных термометрах.
• Пары ртути, которые светятся в тлеющем разряде, используются для заполнения люминесцентных ламп.
• Металл и его сплавы применяют в герметичных выключателях, которые включаются в определённом положении.
• Некоторые химические источники тока и гидродинамические подшипники не обходятся без ртути.
• Вещество может применяться в датчиках положения.
• Иодид металла служит полупроводниковым детектором радиоактивного излучения.
• Бромид ртути используется в атомно-водородной энергетике.
• Соединение элемента с цезием выступает высокоэффективным рабочим телом в ионных двигателях.
• Металлическую ртуть используют как катод для электролитического получения активных металлов и щелочей.
• С помощью вещества перерабатывают вторичный алюминий.
• Соли химического элемента широко используют в лабораториях. Они помогают получить ацетальдегид из ацетилена.
• Каломель, сулему и некоторые другие токсичные соединения с Hg применяются в сельском хозяйстве для протравливания зерна и в качестве пестицидов.

В области медицины вещество практически не используют, поскольку оно считается опасным для жизни человека. В виде консерванта он содержится в малых количествах в вакцинах. В прошлом ртуть использовали в качестве слабительного, мочегонного и антисептического средства.

С 2020 года будет запрещено производство некоторых предметов для бытовых нужд, содержащих токсичный металл, поскольку испарения часто вызывают отравления у людей. Также введут регулирование применения вещества и ограничат многие промышленные процессы и отрасли, связанные с этим химическим элементом.

Ртуть — довольно интересный металл, который проявляет необычные свойства. О нём имеется немало занимательных фактов, однако учёные продолжают изучать особенности «жидкого серебра». Возможно, в будущем этому элементу найдут дополнительное применение и смогут снизить степень его токсичности.

        Hg, химический элемент II группы периодической системы Менделеева, атомный номер 80, атомная масса 200,59; серебристо-белый тяжёлый металл, жидкий при комнатной температуре. В природе Р. представлена семью стабильными изотопами с массовыми числами: 196 (0,2%), 198 (10,0%), 199 (16,8%), 200 (23,1%), 201 (13,2%), 202 (29,8%), 204 (6,9%).

         Историческая справка. Самородная Р. была известна за 2000 лет до н. э. народам Древней Индии и Древнего Китая. Ими же, а также греками и римлянами применялась Киноварь (природная HgS) как краска, лекарственное и косметическое средство. Греческий врач Диоскорид (1 в. н. э.), нагревая киноварь в железном сосуде с крышкой, получил Р. в виде паров, которые конденсировались на холодной внутренней поверхности крышки. Продукт реакции был назван hydrárgyros (от греч. hýdor — вода и árgyros — серебро), т. е. жидким серебром, откуда произошли латинские названия hydrargyrum, а также argentum vivum — живое серебро. Последнее сохранилось в названиях P. quicksilver (англ.) и Quecksilber (нем.). Происхождение русского названия Р. не установлено. Алхимики считали Р. главной составной частью всех металлов. «Фиксация» Р. (переход в твёрдое состояние) признавалась первым условием её превращения в золото. Твёрдую Р. впервые получили в декабре 1759 петербургские академик И. А. Браун и М. В. Ломоносов. Учёным удалось заморозить Р. в смеси из снега и концентрированной азотной кислоты. В опытах Ломоносова отвердевшая Р. оказалась ковкой, как свинец. Известие о «фиксации» Р. произвело сенсацию в учёном мире того времени; оно явилось одним из наиболее убедительных доказательств того, что Р. — такой же металл, как и все прочие.

         Распространение Р. в природе. Р. принадлежит к числу весьма редких элементов, её среднее содержание в земной коре (кларк) близко к 4,5․10^-6% по массе. Приблизительно в таких количествах она содержится в изверженных горных породах. Важную роль в геохимии Р. играет её миграция в газообразном состоянии и в водных растворах. В земной коре Р. преимущественно рассеяна; осаждается из горячих подземных вод, образуя Ртутные руды (содержание Р. в них составляет несколько процентов). Известно 35 ртутных минералов; главнейший из них — киноварь HgS.

         В биосфере Р. в основном рассеивается и лишь в незначительных количествах сорбируется глинами и илами (в глинах и сланцах в среднем 4․10^-5%). В морской воде содержится 3․10^-9% Р.

         Самородная Р., встречающаяся в природе, образуется при окислении киновари в сульфат и разложении последнего, при вулканических извержениях (редко), гидротермальным путём (выделяется из водных растворов).

         Физические и химические свойства Р. — единственный металл, жидкий при комнатной температуре. Твёрдая Р. кристаллизуется в ромбические сингонии, а = 3,463 Å, с = 6,706 Å; плотность твёрдой Р. 14,193 г/см³ (—38,9 °С), жидкой 13,52 г/см³ (20 °С), атомный радиус 1,57 Å, ионный радиус Hg²⁺ 1,10 Å; t_пл — 38,89 °С; t_kип 357,25 °С; удельная теплоемкость при 0 °С 0,139 кдж/(кг ․К) [0,03336 кал/(г․°С)]; при 200 °С 0,133 кдж/(кг․К)[0,0319 кал/(г ․°С)]; температурный коэффициент линейного расширения 1,826․10^-4 (0—100 °С); теплопроводность 8,247вт/(м․К) [0,0197 кал/(см․сек․°C) (при 20°C); удельное электросопротивление при 0°С 94,07․10^-8 ом․м (94,07․10^-6 ом․см). При 4,155 К Р. становится сверхпроводником (см. Сверхпроводимость). Р. диамагнитна, её атомная магнитная восприимчивость равна —0,19․10^-6 (при 18 °С).

         Конфигурация внешних электронов атома Hg 5d ¹⁰6s², в соответствии с чем при химических реакциях образуются катионы Hg²⁺ и Hg₂²⁺. Химическая активность Р. невелика. В сухом воздухе (или кислороде) она при комнатной температуре сохраняет свой блеск неограниченно долго. С кислородом даёт 2 соединения: чёрную закись Hg₂O и красную окись HgO. Hg₂O появляется в виде чёрной плёнки на поверхности Р. при действии озона. HgO образуется при нагревании Hg на воздухе (300—350 °С), а также при осторожном нагревании нитратов Hg (NO₃)₂ или Hg₂(NO₃)₂. Гидроокись Р. практически не образуется. При взаимодействии с металлами, которые Р. смачивает, образуются амальгамы (См. Амальгама). Из сернистых соединений важнейшим является HgS, которую получают растиранием Hg с серным цветом при комнатной температуре, а также осаждением растворов солей Hg²⁺ сероводородом или сульфидом щелочного металла. С галогенами (хлором, иодом) Р. соединяется при нагревании, образуя почти недиссоциирующие, в большинстве ядовитые соединения типа HgX₂. В соляной и разбавленной серной кислотах Р. не растворяется но растворима в царской водке, азотной и горячей концентрированной серной кислотах.

         Почти все соли Hg²⁺ плохо растворимы в воде. К хорошо растворимым относится нитрат Hg (NO₃)₂.

         Большое значение имеют хлориды Р.: Hg₂Cl₂ (Каломель) и HgCl₂ (Сулема) Известны соли окисной Р. цианистой и роданистой кислот, а также ртутная соль гремучей кислоты Hg (ONC)₂, т. н. Гремучая ртуть. При действии аммиака на соли образуются многочисленные Комплексные соединения, например HgCI․2NH₃ (плавкий белый преципитат) и HgNH₂CI (неплавкий белый преципитат). Применение находят Ртутьорганические соединения.

         Получение Р. Ртутные руды (или рудные концентраты), содержащие Р. в виде киновари, подвергают окислительному обжигу

         HgS + O₂ = Hg + SO₂.

         Обжиговые газы, пройдя пылеуловительную камеру, поступают в трубчатый холодильник из нержавеющей стали или монель-металла. Жидкая Р. стекает в железные приёмники. Для очистки сырую Р. пропускают тонкой струйкой через высокий (1—1,5м) сосуд с 10%-ной HNO₃, промывают водой, высушивают и перегоняют в вакууме.

         Возможно также гидрометаллургическое извлечение Р. из руд и концентратов растворением HgS в сернистом натрии с последующим вытеснением Р. алюминием. Разработаны способы извлечения Р. электролизом сульфидных растворов.

         Применение. Р. широко применяется при изготовлении научных приборов (барометры, термометры, манометры, вакуумные насосы, нормальные элементы (См. Нормальный элемент), полярографы, капиллярные электрометры и др.), в ртутных лампах (См. Ртутная лампа), переключателях, выпрямителях; как жидкий катод в производстве едких щелочей и хлора электролизом, в качестве катализатора при синтезе уксусной кислоты, в металлургии для амальгамации (См. Амальгамация) золота и серебра, при изготовлении взрывчатых веществ (см. Гремучая ртуть); в медицине (каломель, сулема, ртутьорганические и другие соединения), в качестве пигмента (киноварь), в сельском хозяйстве (органические соединения Р.) в качестве протравителя семян и гербицида, а также как компонент краски морских судов (для борьбы с обрастанием их организмами). Р. и ее соединения токсичны, поэтому работа с ними требует принятия необходимых мер предосторожности.

С. А. Погодин.

Р. в организме. Содержание Р. в организмах составляет около 10^-6% В среднем в организм человека с пищей ежесуточно поступает 0,02—0,05 мг Р. Концентрация Р. в крови человека составляет в среднем 0,023 мкг/мл, в моче — 0,1—0,2 мкг/мл. В связи с загрязнением воды промышленными отходами в теле многих ракообразных и рыб концентрация Р. (главным образом в виде её органических соединений) может значительно превышать допустимый санитарно-гигиенический уровень. Ионы Р. и её соединения, связываясь с сульфгидрильными группами (См. Сульфгидрильные группы) ферментов, могут инактивировать их. Попадая в организм, Р. влияет на поглощение и обмен микроэлементов — Cu, Zn, Cd, Se. В целом биологическая роль Р. в организме изучена недостаточно.

Ю. И. Раецкая.

Отравления Р. и её соединениями возможны на ртутных рудниках и заводах, при производстве некоторых измерительных приборов, ламп, фармацевтических препаратов, инсектофунгицидов и др.

         Основную опасность представляют пары металлической Р., выделение которых с открытых поверхностей возрастает при повышении температуры воздуха. При вдыхании Р. попадает в кровь. В организме Р. циркулирует в крови, соединяясь с белками; частично откладывается в печени, в почках, селезёнке, ткани мозга и др. Токсическое действие связано с блокированием сульфгидрильных групп тканевых белков, нарушением деятельности головного мозга (в первую очередь, гипоталамуса). Из организма Р. выводится через почки, кишечник, потовые железы и др.

         Острые отравления Р. и её парами встречаются редко. При хронических отравлениях наблюдаются эмоциональная неустойчивость, раздражительность, снижение работоспособности, нарушение сна, дрожание пальцев рук, снижение обоняния, головные боли. Характерный признак отравления — появление по краю дёсен каймы сине-чёрного цвета; поражение дёсен (разрыхлённость, кровоточивость) может привести к гингивиту и стоматиту. При отравлениях органическими соединениями Р. (диэтилмеркурфосфатом, диэтил-ртутью, этилмеркурхлоридом) преобладают признаки одновременного поражения центральной нервной (энцефало-полиневрит) и сердечно-сосудистой систем, желудка, печени, почек.

         Лечение: внутривенное введение 20%-ного раствора гипосульфита (12—15 вливаний на курс), унитиол, фармакологические и физиотерапевтические средства, нормализующие высшую нервную деятельность, курортолечение (Пятигорск, Мацеста и т. п.) и др. Профилактика: замена Р. менее вредными веществами, правильные способы хранения, соблюдение мер безопасности при использовании (герметичность оборудования, рациональная отделка помещений, рабочих поверхностей, эффективная вентиляция), индивидуальная защита; предварительные и периодические медицинские осмотры.

         Препараты Р. находят применение в медицинской практике, главным образом благодаря их антисептическим и мочегонным свойствам. Как мочегонные применяют меркузал, промеран и др. В качестве антисептиков используют сулему (дезинфекция кожи, одежды, предметов ухода за больными и т. п.), диоцид (стерилизация хирургических инструментов и т. п.), цианид и оксицианид Р. (для промываний и спринцеваний при некоторых воспалительных процессах), амидохлорид Р. (в виде мази при заболеваниях кожи), окись Р. жёлтую (в виде мази при заболеваниях глаз и кожи). Применявшиеся ранее для лечения сифилиса препараты Р. в современной практике не используются.

А. А. Каспаров.

Лит.: Мельников С. М., Ртуть, в кн.: Краткая химическая энциклопедия, т. 4, М., 1965; Реми Г., Курс неорганической химии, пер. с нем., т. 2, М., 1966; Рипан Р., Четяну И., Неорганическая химия, пер. с рум., М., 1972; Некрасов Б. В., Основы общей химии, 2 изд., т. 2, М., 1969; Вредные вещества в промышленности, под общ. ред. Н. В. Лазарева, 6 изд., [ч. 2], Л., 1971; Трахтенберг И. М., Хроническое воздействие ртути на организм, К., 1969; Профессиональные болезни, 3 изд., М., 1973.

РТУТЬ (лат. Hydrargyrum), Hg, хи­мич. эле­мент II груп­пы ко­рот­кой фор­мы (12-й груп­пы длин­ной фор­мы) пе­рио­дич. сис­те­мы; ат. н. 80, ат. м. 200,59. При­род­ная Р. со­сто­ит из се­ми ста­биль­ных изо­то­пов: ¹⁹⁶Hg (0,15%), ¹⁹⁸Hg (9,97%), ¹⁹⁹Hg (16,87%), ²⁰⁰Hg (23,10%), ²⁰¹Hg (13,18%), ²⁰²Hg (29,86%), ²⁰⁴Hg (6,87%). Ис­кус­ст­вен­но по­лу­че­ны ра­дио­изо­то­пы с мас­со­вы­ми чис­ла­ми 174–208.

Историческая справка

Р. – один из се­ми ме­тал­лов, из­вест­ных с древ­ней­ших вре­мён в Ин­дии, Ки­тае, Егип­те (за 2000 лет до н. э.). Не­ред­ко её на­хо­ди­ли в са­мо­род­ном ви­де, ча­ще по­лу­ча­ли об­жи­гом при­род­ной ки­но­ва­ри. Р. и её со­еди­не­ния ис­поль­зо­ва­лись в ме­ди­ци­не, из ки­но­ва­ри де­ла­ли крас­ные крас­ки (вер­миль­он). Древ­ние гре­ки и рим­ля­не ис­поль­зо­ва­ли Р. для из­вле­че­ния зо­ло­та и се­реб­ра (амаль­га­ми­ро­ва­ние), зна­ли о ток­сич­но­сти са­мой Р. и её со­еди­не­ний, напр. хло­ри­да рту­ти(II) – су­ле­мы. Ал­хи­ми­ки счи­та­ли Р. гл. со­став­ной ча­стью всех ме­тал­лов и пред­по­ла­га­ли, что из неё мож­но по­лу­чить зо­ло­то. Лат. назв. об­ра­зо­ва­но от греч. ὑδράργυρος (ὕδωρ – во­да и ἄργυρος  – се­реб­ро; «жид­кое те­ку­чее се­реб­ро»), дан­но­го в 1 в. н. э. Дио­ско­ри­дом. Совр. англ. (mercury) и франц. (mercure) на­зва­ния Р. про­изош­ли от име­ни др.-рим. бо­га тор­гов­ли и по­слан­ни­ка бо­гов Мер­ку­рия (Mercurius; в ал­хи­мии Р. обо­зна­ча­лась ас­тро­но­мич. сим­во­лом пла­не­ты Мер­ку­рий). Вы­де­ле­ние Р. в чис­том ви­де опи­са­но Г. Бранд­том в 1735.

Распространённость в природе

Со­дер­жа­ние Р. в зем­ной ко­ре 7,0·10^–6% по мас­се, в мор. во­де 0,03 мг/м³, в ат­мо­сфе­ре 2·10^–3 мг/м³. Р. от­но­сят к рас­се­ян­ным эле­мен­там (в кон­цен­трир. ви­де в ме­сто­ро­ж­де­ни­ях на­хо­дит­ся толь­ко 0,02% всей Р.); в при­ро­де встре­ча­ет­ся в сво­бод­ном со­стоя­нии (ртуть са­мо­род­ная). Об­ра­зу­ет бо­лее 30 ми­не­ра­лов. Осн. руд­ный ми­не­рал – ки­но­варь HgS. Ми­не­ра­лы Р. в ви­де изо­морф­ных при­ме­сей встре­ча­ют­ся в квар­це, хал­це­до­не, кар­бо­на­тах, слю­дах, свин­цо­во-цин­ко­вых ру­дах. В об­мен­ных про­цес­сах гид­ро­сфе­ры, ли­то­сфе­ры, ат­мо­сфе­ры уча­ст­ву­ет боль­шое ко­ли­че­ст­во Р. См. так­же Ртут­ные ру­ды.

Свойства

Кон­фи­гу­ра­ция внеш­них элек­трон­ных обо­ло­чек ато­ма Р. 4f¹⁴5s²5p⁶5d¹⁰6s²; в со­еди­не­ни­ях обыч­но про­яв­ля­ет сте­пень окис­ле­ния +1 и +2; энер­гии ио­ни­за­ции Hg⁰→Hg⁺→Hg²⁺→Hg³⁺ со­от­вет­ст­вен­но рав­ны 1007, 1809 и 3300 кДж/моль; элек­тро­от­ри­ца­тель­ность по По­лин­гу 1,9; атом­ный ра­ди­ус 155 пм, ко­ва­лент­ный ра­ди­ус 149 пм, ион­ные ра­диу­сы (в скоб­ках ука­за­но ко­ор­ди­нац. чис­ло) Hg⁺ 111 пм (3), 133 пм (6), Hg²⁺ 83 пм (2), 110 пм (4), 116 пм (6), 128 пм (8).

Р. – се­реб­ри­сто-бе­лый ме­талл, ле­ту­чий уже при ком­нат­ной темп-ре, в па­рах бес­цвет­ный; един­ст­вен­ный из ме­тал­лов – жид­кий при ком­нат­ной темп-ре; t_пл –38,87 °C, t_кип 356,58 °C; плот­ность (кг/м³): 13 595,1 (0 °C), 13 545,7 (20 °C), 13533,6 (25 °C), 13411,8 (75 °C), 13351,5 (100 °C). Твёр­дая Р. – бес­цвет­ные кри­стал­лы; до 79 К су­ще­ст­ву­ет ром­бо­эд­ри­че­ская кри­стал­лич. α -мо­ди­фи­ка­ция, ни­же – β-Hg с тет­ра­го­наль­ной объ­ём­но­цен­трир. ре­шёт­кой; плот­ность твёр­дой Р. 14193 кг/м³ (–38,9 °C). Те­п­ло­ём­кость 27,98 Дж/(моль·К), тем­пе­ра­тур­ный ко­эф. ли­ней­но­го рас­ши­ре­ния 41·10^–6 К^–1 (195–234 К). Диа­маг­не­тик. Темп-ра пе­ре­хо­да в сверх­про­во­дя­щее со­стоя­ние α-Hg 4,153 К, β-Hg 3,949 К. Рас­тво­ри­мость Р. (г в 100 г): в во­де 6·10^–6 (25 °C), бен­зо­ле 2·10^–7 (20 °C), ди­ок­са­не 7,0·10^–7 (25 °C). Р. не сма­чи­ва­ет стек­ло.

Р. окис­ля­ет­ся до HgO ки­сло­ро­дом (при темп-ре вы­ше 300 °C), озо­ном – при ком­нат­ной темп-ре, во влаж­ном воз­ду­хе по­кры­ва­ет­ся плён­кой ок­си­да (рту­ти ок­сид). Не реа­ги­ру­ет с Н₂, N₂, P, As, С, Si, В, Ge, с су­хи­ми НСl, HF, H₂S, NH₃, PH₃ и AsH₃ при темп-ре ни­же 200 °C; с НВr, HI, H₂Se, тон­ко­из­мель­чён­ной S взаи­мо­дей­ст­ву­ет уже при ком­нат­ной темп-ре. Р. не взаи­мо­дей­ст­ву­ет с раз­бав­лен­ны­ми H₂SO₄ и HCl; реа­ги­ру­ет с цар­ской вод­кой, HNO₃ и кон­цен­трир. H₂SO₄. С га­ло­ге­на­ми Р. ак­тив­но взаи­мо­дей­ст­ву­ет, об­ра­зуя га­ло­ге­ни­ды (см., напр., Рту­ти хло­ри­ды), с халь­ко­ге­на­ми – халь­ко­ге­ни­ды (HgS, HgSe, HgTe). Р. об­ра­зу­ет спла­вы – амаль­га­мы со мно­ги­ми ме­тал­ла­ми (кро­ме V, Fe, Mo, Cs, Nb, Та, W), да­ёт ин­тер­ме­тал­лич. со­еди­не­ния (мер­ку­ри­ды). Со­ли Hg(I) су­ще­ст­ву­ют в ви­де ди­ме­ров, ка­ти­он Hg₂²⁺ со­хра­ня­ет­ся как в кри­стал­лич. ре­шёт­ке, так и в рас­тво­ре; су­ще­ст­ву­ют га­ло­ге­ни­ды Hg₂X₂ (X – F, Cl, Br, I), в ча­ст­но­сти хло­рид Hg₂Cl₂ (ка­ло­мель), нит­рат Hg₂(NO₃)₂ и его кри­стал­ло­гид­рат Hg₂(NO₃)₂·2H₂O, суль­фат Hg₂SO₄ и др. Со­ли Hg(II) – нит­рат Hg(NO₃)₂, суль­фат HgSO₄; ди­га­ло­ге­ни­ды Р. име­ют пре­им. ко­ва­лент­ный ха­рак­тер, су­ще­ст­ву­ют в вод­ном рас­тво­ре поч­ти ис­клю­чи­тель­но в мо­ле­ку­ляр­ной фор­ме, склон­ны об­ра­зо­вы­вать га­ло­ге­нид­ные ком­плек­сы. Мн. со­еди­не­ния Р. ле­ту­чи, раз­ла­га­ют­ся на све­ту, при на­гре­ва­нии, лег­ко вос­ста­нав­ли­ва­ют­ся. См. так­же Ртуть­ор­га­ни­че­ские со­еди­не­ния.

Биологическая роль

Р. вы­со­ко­ток­сич­на для лю­бых форм жиз­ни. Па­ры́ и со­еди­не­ния Р. чрез­вы­чай­но ядо­ви­ты, на­ка­п­ли­ва­ют­ся в ор­га­низ­ме, лег­ко сор­би­ру­ют­ся лё­гоч­ной тка­нью, по­па­да­ют в кровь, под­вер­га­ют­ся фер­мен­та­тив­но­му окис­ле­нию до ио­нов Р., ко­то­рые об­ра­зу­ют со­еди­не­ния с мо­ле­ку­ла­ми бел­ка, фер­мен­та­ми, на­ру­ша­ют об­мен ве­ществ, по­ра­жа­ют нерв­ную сис­те­му. ПДК Р. в воз­ду­хе ра­бо­чей зо­ны 0,01 мг/м³, в ат­мо­сфер­ном воз­ду­хе 0,0003 мг/м³, в во­де во­до­ёмов 0,0005 мг/дм³, в поч­ве 2,1 мг/кг. При ра­бо­те с Р. не­об­хо­ди­ма пол­ная гер­ме­ти­за­ция ап­па­ра­ту­ры. Для хра­не­ния Р. ис­поль­зу­ют сталь­ные бал­ло­ны. Слу­чай­но про­ли­тую Р. не­об­хо­ди­мо со­брать мед­ной пла­стин­кой, за­тем об­ра­бо­тать по­верх­ность рас­тво­ром FeCl₃ (де­мер­ку­ри­за­ция).

Ес­те­ст­вен­ные ис­точ­ни­ки за­гряз­не­ния сре­ды – ис­па­ре­ние со всей по­верх­но­сти су­ши, воз­гон­ка из со­еди­не­ний, на­хо­дя­щих­ся глу­бо­ко в тол­ще зем­ной ко­ры, вул­ка­нич. дея­тель­ность; ан­тро­по­ген­ные ис­точ­ни­ки – ме­тал­лур­гия, сжи­га­ние ор­га­нич. то­п­лив, про­из-во хло­ра и со­ды, бы­то­вые (сжи­га­ние му­со­ра, сточ­ные во­ды и т. д.) и др. Эко­ло­гич. по­след­ст­вия про­яв­ля­ют­ся пре­ж­де все­го в вод­ной сре­де – по­дав­ля­ет­ся жиз­не­дея­тель­ность од­но­кле­точ­ных мор­ских ор­га­низ­мов и рыб, на­ру­ша­ет­ся фо­то­син­тез, ас­си­ми­ли­ру­ют­ся нит­ра­ты, фос­фа­ты, со­еди­не­ния ам­мо­ния и т. д.

Получение

Р. по­лу­ча­ют гл. обр. об­жи­гом ки­но­ва­ри HgS при 700–800 °C. Вос­ста­нов­лен­ная Р. уда­ля­ет­ся из зо­ны ре­ак­ции с от­хо­дя­щи­ми га­за­ми, очи­ща­ет­ся в элек­тро­фильт­рах от взве­шен­ных час­тиц и со­би­ра­ет­ся в кон­ден­са­то­рах. Вы­ход Р. бо­лее 80%. Для по­лу­че­ния тех­нич. про­дук­та Р. фильт­ру­ют че­рез по­рис­тые пе­ре­го­род­ки, ке­ра­мич. фильт­ры, сук­но, зам­шу, по­сле­до­ва­тель­но про­мы­ва­ют рас­тво­ра­ми ще­ло­чей, азот­ной ки­сло­той, рас­тво­ра­ми Hg(NO₃)₂ и пе­ре­го­ня­ют. Гид­ро­ме­тал­лур­гич. из­вле­че­ние Р. ве­дут об­ра­бот­кой ки­но­ва­ри вод­ны­ми ще­лоч­ны­ми рас­тво­ра­ми суль­фи­да или по­ли­суль­фи­да на­трия. Об­ра­зо­вав­шие­ся рас­тво­ры тио­со­лей Р. под­вер­га­ют элек­тро­ли­зу. Для по­лу­че­ния осо­бо чис­той Р. ис­поль­зу­ют че­ты­рёх­ста­дий­ное элек­тро­хи­мич. ра­фи­ни­ро­ва­ние в элек­тро­ли­зё­рах с ртут­ны­ми элек­тро­да­ми.

Объ­ём ис­поль­зо­ва­ния Р. – ок. 4000 т/год.

Применение

Р. – ма­те­ри­ал ка­то­дов при элек­тро­хи­мич. по­лу­че­нии ед­ких ще­ло­чей и хло­ра, при­ме­ня­ет­ся в по­ля­ро­гра­фии, в про­из-ве ртут­ных вен­ти­лей, га­зо­раз­ряд­ных ис­точ­ни­ков све­та (лю­ми­нес­цент­ных и ртут­ных ламп), диф­фу­зи­он­ных ва­ку­ум­ных на­со­сов, кон­троль­но-из­ме­рит. при­бо­ров (тер­мо­мет­ров, ба­ро­мет­ров, ма­но­мет­ров и др.); для оп­ре­де­ле­ния чис­то­ты фто­ра, а так­же его кон­цен­тра­ции в га­зах. Со­еди­не­ния Р. ис­поль­зу­ют в мер­ку­ри­мет­ри­че­ском и мер­ку­ро­мет­ри­че­ском ме­то­дах объ­ём­но­го ана­ли­за, для чер­не­ния ла­ту­ни, как ком­по­нент гла­зу­рей, в со­ста­ве элек­тро­ли­та в хи­мич. ис­точ­ни­ках то­ка, взрыв­ча­тых ве­ществ (гре­му­чая ртуть) и др.