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Mercury is a
chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elements cannot be broken down into simp ...
with the
symbol A symbol is a mark, sign, or word In linguistics, a word of a spoken language can be defined as the smallest sequence of phonemes that can be uttered in isolation with semantic, objective or pragmatics, practical meaning (linguistics), m ...
Hg and
atomic number 300px, The Rutherford–Bohr model of the hydrogen atom () or a hydrogen-like ion (). In this model it is an essential feature that the photon energy (or frequency) of the electromagnetic radiation emitted (shown) when an electron jumps from one ...
80. It is commonly known as quicksilver and was formerly named hydrargyrum ( ). A
heavy Heavy may refer to: Measures * Heavy (aeronautics), a term used by pilots and air traffic controllers to refer to aircraft capable of 300,000 lbs or more takeoff weight * Heavy, a characterization of objects with substantial weight In scien ...
, silvery
d-block A block of the periodic table The periodic table, also known as the periodic table of (the) chemical elements, is a tabular display of the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodi ...
element, mercury is the only metallic element that is liquid at
standard conditions for temperature and pressure Standard temperature and pressure (STP) are standard Standard may refer to: Flags * Colours, standards and guidons * Standard (flag), a type of flag used for personal identification Norm, convention or requirement * Standard (metrology), ...
; the only other element that is liquid under these conditions is the
halogen The halogens () are a group A group is a number A number is a mathematical object used to counting, count, measurement, measure, and nominal number, label. The original examples are the natural numbers 1, 2, 3, 4, and so forth. Numbers can b ...

halogen
bromine Bromine is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elemen ...

bromine
, though metals such as
caesium Caesium (IUPAC spelling) (American and British English spelling differences, also spelled cesium in American English) is a chemical element with the Symbol (chemistry), symbol Cs and atomic number 55. It is a soft, silvery-golden alkali ...

caesium
,
gallium Gallium is a chemical element with the Symbol (chemistry), symbol Ga and atomic number 31. Discovered by France, French chemist Paul-Émile Lecoq de Boisbaudran in 1875, Gallium is in boron group, group 13 of the periodic table and is ...

gallium
, and
rubidium Rubidium is the chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science th ...

rubidium
melt just above
room temperature Colloquially, room temperature is the range of air temperature Temperature is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy, present in all matter, which is the source of the occurrence of heat ...
. Mercury occurs in deposits throughout the world mostly as
cinnabar Cinnabar () or cinnabarite (), likely deriving from the grc, κιννάβαρι (), is the bright scarlet to brick-red form of mercury(II) sulfide (HgS). It is the most common source ore for refining elemental mercury, and is the historic sou ...

cinnabar
( mercuric sulfide). The red pigment
vermilion File:Lacquerware-roundbox-w-children.jpg, A Chinese "cinnabar red" carved lacquer box from the Qing dynasty (1736–1795), National Museum of China, Beijing Vermilion (sometimes spelled vermillion) is both a brilliant red or scarlet (color), sc ...

vermilion
is obtained by grinding natural cinnabar or synthetic mercuric sulfide. Mercury is used in
thermometer (mercury-in-glass thermometer) for measurement of room temperature. A thermometer is a device that temperature measurement, measures temperature or a temperature gradient A temperature gradient is a physical quantity that describes in which dir ...

thermometer
s,
barometer A barometer is a scientific instrument that is used to measure air pressure in a certain environment. Pressure tendency can forecast short term changes in the weather. Many measurements of air pressure are used within surface weather analysis to ...

barometer
s,
manometer Pressure measurement is the analysis of an applied force In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that st ...

manometer
s,
sphygmomanometer A sphygmomanometer ( ), also known as a blood pressure monitor, or blood pressure gauge, is a device used to measure blood pressure, composed of an inflatable cuff to collapse and then release the artery under the cuff in a controlled manner, and ...

sphygmomanometer
s, float valves,
mercury switch A mercury switch is an electrical switch In electrical engineering Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems which use electricity, electronic ...

mercury switch
es,
mercury relay A mercury relay (mercury displacement relay, mercury contactor) is a relay that uses mercury (element), mercury as the switching element. They are used as high-current switches or contactors, where contact erosion from constant cycling would be a ...

mercury relay
s,
fluorescent lamp A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor that uses to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet light that then causes a coating ...

fluorescent lamp
s 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 In chemistry, alcohol is an organic compound that carries at least one hydroxyl functional group (−OH) bound to a Saturated and unsaturated compounds, saturated carbon atom. The term alcohol originally referred to the primary alcohol ethan ...

alcohol
- or
galinstan Galinstan is a brand name for a eutectic alloy An alloy is an admixture of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractur ...
-filled glass thermometers and
thermistor A thermistor is a type of resistor whose resistance is strongly dependent on temperature Temperature is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy, present in all matter, which is the source ...

thermistor
- or
infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior ...
-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 Dental restoration, dental fillings, or simply fillings, are treatments used to restore the function, integrity, and morphology of missing tooth structure resulting from Dental caries, caries or external trauma as well as to the replacement of suc ...
in some locales. It is also used in
fluorescent lighting light. Fluorescence is the emission of light Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that can be visual perception, perceived by the human eye. Visible light is usually defi ...
. Electricity passed through mercury vapor in a fluorescent lamp produces short-wave
ultraviolet light Ultraviolet (UV) is a form of electromagnetic radiation with wavelength In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural s ...
, which then causes the phosphor in the tube to
fluoresce light. Fluorescence is the emission of light Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that can be visual perception, perceived by the human eye. Visible light is usually defi ...
, making visible light.
Mercury poisoning Mercury poisoning is a type of metal poisoning due to exposure to mercury. Symptoms depend upon the type, dose, method, and duration of exposure. They may include muscle weakness, poor coordination, numbness in the hands and feet, skin rashes, ...
can result from exposure to water-soluble forms of mercury (such as
mercuric chloride Mercury(II) chloride or mercuric chloride (historically "corrosive sublimate") is the chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atom ...
or
methylmercury Methylmercury (sometimes methyl mercury) is an extremely toxic organometallic cation An ion () is a particle, atom or molecule with a net electric charge, electrical charge. The charge of the electron is considered negative by convention ...

methylmercury
), by inhalation of mercury vapor, or by ingesting any form of mercury.


Properties


Physical properties

Mercury is a heavy, silvery-white liquid metal. Compared to other metals, it is a poor conductor of heat, but a fair conductor of electricity.Hammond, C.
The Elements
in
It has a freezing point of −38.83 °C and a
boiling point The boiling point of a substance is the temperature at which the vapor pressure 280px, The ''pistol test tube'' experiment. The tube contains alcohol and is closed with a piece of cork. By heating the alcohol, the vapors fill in the space, inc ...
of 356.73 °C, both the lowest of any stable metal, although preliminary experiments on
copernicium Copernicium is a syntheticA synthetic is an artificial material produced by organic chemistry, organic chemical synthesis. Synthetic may also refer to: In the sense of both "combination" and "artificial" * Synthetic chemical or synthetic c ...

copernicium
and
flerovium Flerovium is a superheavy artificial chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms t ...

flerovium
have indicated that they have even lower boiling points (copernicium being the element below mercury in the periodic table, following the trend of decreasing boiling points down group 12). 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. A complete explanation of mercury's extreme volatility delves deep into the realm of
quantum physics Quantum mechanics is a fundamental theory A theory is a rational Rationality is the quality or state of being rational – that is, being based on or agreeable to reason Reason is the capacity of consciously making sense of things, ...
, but it can be summarized as follows: mercury has a unique
electron configuration In atomic physics and quantum chemistry Quantum chemistry, also called molecular quantum mechanics, is a branch of chemistry focused on the application of quantum mechanics to chemical systems. Understanding electronic structure and molecul ...
where electrons fill up all the available 1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d, 4f, 5s, 5p, 5d, and 6s subshells. Because this configuration strongly resists removal of an electron, mercury behaves similarly to
noble gas The noble gases (historically also the inert gases; sometimes referred to as aerogens) make up a class of chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that m ...
es, which form weak bonds and hence melt at low temperatures. The stability of the 6s shell is due to the presence of a filled 4f shell. An f shell poorly screens the
nuclear charge The effective nuclear charge (often symbolized as Z_ or Z^\ast) is the net positive charge experienced by an electron The electron is a subatomic particle, symbol or , whose electric charge Electric charge is the physical property of mat ...
that increases the attractive
Coulomb interaction ''F'' between two point charge A point particle (ideal particle or point-like particle, often spelled pointlike particle) is an idealization of particle In the Outline of physical science, physical sciences, a particle (or corpuscule in old ...
of the 6s shell and the nucleus (see
lanthanide contraction The lanthanide contraction is the greater-than-expected decrease in ionic radii of the elements in the lanthanide The lanthanide () or lanthanoid () series of chemical elements comprises the 15 metallic chemical element Image:Simple Periodic ...
). The absence of a filled inner f shell is the reason for the somewhat higher melting temperature of
cadmium Cadmium is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical eleme ...

cadmium
and
zinc Zinc is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

zinc
, although both these metals still melt easily and, in addition, have unusually low boiling points.


Chemical properties

Mercury does not react with most acids, such as dilute
sulfuric acid Sulfuric acid (American spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography English orthogra ...

sulfuric acid
, although oxidizing acids such as concentrated sulfuric acid and
nitric acid Nitric acid (), also known as ''aqua fortis'' (Latin for "strong water") and spirit of niter, is a highly corrosive mineral acid. The pure compound is colorless, but older samples tend to acquire a yellow cast due to decomposition into nitroge ...

nitric acid
or
aqua regia ''Aqua regia'' (; from Latin, "regal water" or "Royal water") is a mixture of nitric acid and hydrochloric acid, optimally in a molar concentration, molar ratio of 1:3.The relative concentrations of the two acids in water differ; values could be ...

aqua regia
dissolve it to give
sulfate The sulfate or sulphate ion is a polyatomic anion An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having ...
,
nitrate Nitrate is a polyatomic ion A polyatomic ion, also known as a molecular ion, is a covalently bonded A covalent bond is a chemical bond A chemical bond is a lasting attraction between atoms, ions or molecules that enables the format ...
, and
chloride The chloride ion An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects th ...

chloride
. Like silver, mercury reacts with atmospheric
hydrogen sulfide Hydrogen sulfide is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by havi ...

hydrogen sulfide
. Mercury reacts with solid sulfur flakes, which are used in mercury spill kits to absorb mercury (spill kits also use
activated carbon Activated carbon, also called activated charcoal, is a form of carbon Carbon (from la, carbo "coal") is a chemical element with the Symbol (chemistry), symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—making f ...

activated carbon
and powdered zinc).


Amalgams

Mercury dissolves many metals such as
gold Gold is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elemen ...

gold
and
silver Silver is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical ele ...

silver
to form amalgams.
Iron Iron () is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behav ...

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 Manganese is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical e ...

manganese
,
copper Copper is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elem ...

copper
and
zinc Zinc is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

zinc
are also resistant in forming amalgams. Other elements that do not readily form amalgams with mercury include
platinum Platinum is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical el ...

platinum
.
Sodium amalgamSodium amalgam, commonly denoted Na(Hg), is an alloy of mercury (element), mercury and sodium. The term amalgam (chemistry), amalgam is used for alloys, intermetallic compounds, and solutions (both solid solutions and liquid solutions) involving merc ...
is a common reducing agent in
organic synthesis Organic synthesis is a special branch of chemical synthesis As a topic of , chemical synthesis (or combination) is the artificial execution of s to obtain one or several s. This occurs by and chemical manipulations usually involving one or mo ...

organic synthesis
, and is also used in
high-pressure sodium A sodium-vapor lamp is a gas-discharge lamp Gas-discharge lamps are a family of artificial light sources that generate light by sending an electric discharge through an ionized gas, a plasma. Typically, such lamps use a noble gas ( argon, ...
lamps. Mercury readily combines with
aluminium Aluminium (aluminum in and ) is a with the  Al and  13. Aluminium has a density lower than those of other common , at approximately one third that of . It has a great affinity towards , and of on the surface when exposed to air ...

aluminium
to form a mercury-aluminium amalgam when the two pure metals come into contact. Since the amalgam destroys the
aluminium oxide Aluminium oxide is a chemical compound of aluminium and oxygen with the chemical formula 23. It is the most commonly occurring of several Aluminium oxide (compounds), aluminium oxides, and specifically identified as aluminium(III) oxide. It is ...

aluminium oxide
layer which protects metallic aluminium from oxidizing in-depth (as in iron
rust Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous ferric oxides, hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxi ...

rust
ing), 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. Mercury embrittlement is the most common type of liquid metal embrittlement.


Isotopes

There are seven stable
isotope Isotopes are two or more types of atoms that have the same atomic number 300px, The Rutherford–Bohr model of the hydrogen atom () or a hydrogen-like ion (). In this model it is an essential feature that the photon energy (or frequency) of ...
s of mercury, with being the most abundant (29.86%). The longest-lived
radioisotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide A nuclide (or nucleide, from nucleus, also known as nuclear species) is a class of atoms characterized by their number of proton A proton is a subatomic par ...
s are with a
half-life Half-life (symbol ''t''1⁄2) is the time required for a quantity to reduce to half of its initial value. The term is commonly used in nuclear physics Nuclear physics is the field of physics Physics is the natural science that studies ...
of 444 years, and with a half-life of 46.612 days. Most of the remaining radioisotopes have half-lives that are less than a day. and are the most often studied
NMR Nuclear magnetic resonance (NMR) is a physical phenomenon A phenomenon (; plural phenomena) is an observable In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ...
-active nuclei, having spins of and respectively.


Etymology

"Hg" is the modern
chemical symbol Chemical symbols are the abbreviations used in chemistry Chemistry is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, suc ...
for mercury. It is an abbreviation of , a
romanized Romanization or romanisation, in linguistics Linguistics is the scientific study of language, meaning that it is a comprehensive, systematic, objective, and precise study of language. Linguistics encompasses the analysis of every aspec ...
form of the
ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers simply as Greek (, ), refers collectively to the diale ...
word (), which is a compound meaning "water-silver" (from - (-), the root of 'water', and () 'silver'). Like English quicksilver ("live-silver"), it was named this because it was both liquid and shiny. The chemical name comes from the planet
Mercury Mercury usually refers to: * Mercury (planet) Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets. It is named after the Roman g ...

Mercury
. In alchemy, the seven metals known before the 16th century were associated with the seven planets, and quicksilver was associated with the fastest planet, which had been named after the Roman god
Mercury Mercury usually refers to: * Mercury (planet) Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets. It is named after the Roman g ...
, who was associated with speed and mobility. The astrological symbol for the planet became one of the
alchemical symbol 's 1775 ''Dissertation on Elective Affinities'' Alchemical symbols, originally devised as part of alchemy, were used to denote some elements and some compounds until the 18th century. Although notation like this was mostly standardized, style and ...
s 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.


History

Mercury was found in
Egyptian Egyptian describes something of, from, or related to Egypt. Egyptian or Egyptians may refer to: Nations and ethnic groups * Egyptians, a national group in North Africa ** Egyptian culture, a complex and stable culture with thousands of years of r ...

Egyptian
tombs that date from 1500 BC. In
China China (), officially the People's Republic of China (PRC; ), is a country in East Asia East Asia is the eastern region of Asia Asia () is Earth's largest and most populous continent, located primarily in the Eastern Hemisphere ...

China
and
Tibet Tibet (; ; ) is a region in East Asia covering much of the Tibetan Plateau spanning about . It is the traditional homeland of the Tibetan people as well as some other ethnic groups such as Monpa people, Monpa, Tamang people, Tamang, Qia ...

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. The first emperor of a unified China, Qín Shǐ Huáng Dì—allegedly buried in a
tomb A tomb ( grc-gre, τύμβος ''tumbos'') is a repository for the remains of the dead. It is generally any structurally enclosed interment space or burial chamber, of varying sizes. Placing a corpse into a tomb can be called ''immuremen ...
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 Jade is a mineral, much used in some cultures as jewellery and for ornaments, mostly known for its green varieties, though it appears naturally in other colors as well, notably yellow and white. Jade can refer to either of two different silica ...

jade
mixture formulated by
QinQin may refer to: Dynasties and states * Qin (state) (秦), a major state during the Zhou Dynasty of ancient China * Qin dynasty (秦), founded by the Qin state in 221 BC and ended in 206 BC * Daqin (大秦), ancient Chinese name for the Roman Empi ...

Qin
alchemists intended as an elixir of immortality.
Khumarawayh ibn Ahmad ibn Tulun Abu 'l-Jaysh Khumārawayh ibn Aḥmad ibn Ṭūlūn ( ar, أبو الجيش خمارويه بن أحمد بن طولون; 864 – 18 January 896) was a son of the founder of the Tulunid dynasty The Tulunids (), were a mamluk Mamluk (Arabic ...
, the second
Tulunid The Tulunids (), were a Mamluk Mamluk ( ar, مملوك, mamlūk (singular), , ''mamālīk'' (plural), translated as "one who is owned", meaning "History of slavery in the Muslim world, slave", also Arabic transliteration, transliterated as ' ...
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. In November 2014 "large quantities" of mercury were discovered in a chamber 60 feet below the 1800-year-old pyramid known as the "," "the third largest pyramid of
Teotihuacan Teotihuacan (Spanish language, Spanish: ''Teotihuacán'') (; ) is an ancient Mesoamerican city located in a sub-valley of the Valley of Mexico, which is located in the State of Mexico, northeast of modern-day Mexico City. Teotihuacan is ...

Teotihuacan
," Mexico along with "jade statues, jaguar remains, a box filled with carved shells and rubber balls." The
ancient Greeks Ancient Greece ( el, Ἑλλάς, Hellás) was a civilization belonging to a period of History of Greece, Greek history from the Greek Dark Ages of the 12th–9th centuries BC to the end of Classical Antiquity, antiquity ( AD 600). This era was ...
used
cinnabar Cinnabar () or cinnabarite (), likely deriving from the grc, κιννάβαρι (), is the bright scarlet to brick-red form of mercury(II) sulfide (HgS). It is the most common source ore for refining elemental mercury, and is the historic sou ...

cinnabar
(mercury sulfide) in ointments; the
ancient Egyptians Ancient Egypt was a civilization  A civilization (or civilisation) is a complex society A complex society is a concept that is shared by a range of disciplines including anthropology, archaeology, history and sociology to descri ...
and the
Romans Roman or Romans usually refers to: *Rome , established_title = Founded , established_date = 753 BC , founder = King Romulus , image_map = Map of comune of Rome (metropolitan city of Capital Rome, region Lazio, ...

Romans
used it in
cosmetics Cosmetics are constituted mixtures of chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and take ...
. In
Lamanai Lamanai (from ''Lama'anayin'', "submerged crocodile" in Yucatec Maya) is a Mesoamerica Mesoamerica is a historical region and cultural area in North America North America is a continent entirely within the Northern Hemisphere and a ...

Lamanai
, once a major city of the
Maya civilization The Maya civilization () was a Mesoamerica Mesoamerica is a historical and important region In geography, regions are areas that are broadly divided by physical characteristics ( physical geography), human impact characteristics ( human ...
, a pool of mercury was found under a marker in a
Mesoamerican ballcourt A Mesoamerican ballcourt is a large masonry structure of a type used in Mesoamerica for over 2,700 years to play the Mesoamerican ballgame, particularly the hip-ball version of the ballgame. More than 1,300 ballcourts have been identified, 60% in t ...
. By 500 BC mercury was used to make amalgams (Medieval Latin ''amalgama'', "alloy of mercury") with other metals.
Alchemists File:Aurora consurgens zurich 044 f-21v-44 dragon-pot.jpg, Depiction of Ouroboros from the alchemical treatise ''Aurora consurgens'' (15th century), Zentralbibliothek Zürich, Switzerland Alchemy (from Arabic: ''al-kīmiyā''; from Ancient Gree ...
thought of mercury as the First Matter from which all metals were formed. They believed that different
metals A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts Electrical resistivity and conductivity, e ...
could be produced by varying the quality and quantity of
sulfur Sulfur (in nontechnical British English: sulphur) is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: th ...

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. The mines in (Spain),
Monte Amiata Mount Amiata is the largest of the lava dome In volcanology, a lava dome is a circular mound-shaped protrusion resulting from the slow Extrusive rock, extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly ...
(Italy), and
Idrija Idrija (, in older sources ''Zgornja Idrija''; german: (Ober)idria, it, Idria) is a town in western Slovenia Slovenia ( ; sl, Slovenija ), officially the Republic of Slovenia (Slovene: , abbr.: ''RS''), is a country in Central Europe. I ...

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.


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). 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 A native metal is any metal that is found pure in its metallic form in nature. Metals that can be found as native element mineral, native deposits singly or in alloys include aluminium, antimony, arsenic, bismuth, cadmium, chromium, cobalt, indiu ...
(rare) or in
cinnabar Cinnabar () or cinnabarite (), likely deriving from the grc, κιννάβαρι (), is the bright scarlet to brick-red form of mercury(II) sulfide (HgS). It is the most common source ore for refining elemental mercury, and is the historic sou ...

cinnabar
, metacinnabar,
sphalerite Sphalerite is a sulfide mineral The sulfide minerals are a class of s containing (S2−) or (S22−) as the major . Some sulfide minerals are economically important as metal s. The sulfide class also includes the , the , the , the , the bi ...

sphalerite
, corderoite, livingstonite and other minerals, with cinnabar (HgS) being the most common ore. Mercury ores often in hot springs or other volcano, volcanic regions. 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. 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. 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 Idrija (, in older sources ''Zgornja Idrija''; german: (Ober)idria, it, Idria) is a town in western Slovenia Slovenia ( ; sl, Slovenija ), officially the Republic of Slovenia (Slovene: , abbr.: ''RS''), is a country in Central Europe. I ...

Idrija
) and Spain (), shut down due to the fall of the price of mercury. Nevada's McDermitt, Nevada-Oregon, 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 (unit), flask. 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. 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. 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. 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. 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 County Park, Almaden Quicksilver Mine and created a county park on the site, after conducting extensive safety and environmental analysis of the property.


Chemistry

Mercury exists in two oxidation states, I and II. Despite claims otherwise, Hg(III) and Hg(IV) compounds remain unknown, though short-lived Hg(III) has been achieved through electrochemical oxidation.


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, Hg. Stable derivatives include the chloride and nitrate. Treatment of Hg(I) compounds complexation with strong ligands such as sulfide, cyanide, etc. induces disproportionation to and elemental mercury. 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 .


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 sublimation (chemistry), sublimating white solid. HgCl2 forms coordination complexes that are typically tetrahedral, e.g. . 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. Hydroxides of mercury are poorly characterized, as they are for its neighbors gold and silver. Being a HSAB, 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 Cinnabar () or cinnabarite (), likely deriving from the grc, κιννάβαρι (), is the bright scarlet to brick-red form of mercury(II) sulfide (HgS). It is the most common source ore for refining elemental mercury, and is the historic sou ...

cinnabar
and is the brilliant pigment vermilion, vermillion. Like ZnS, HgS crystallizes in two Polymorphism (materials science), forms, the reddish cubic form and the black zinc blende form. The latter sometimes occurs naturally as metacinnabar. 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. Mercury(II) salts form a variety of complex derivatives with ammonia. These include Millon's base (Hg2N+), the one-dimensional polymer (salts of )), and "fusible white precipitate" or [Hg(NH3)2]Cl2. Known as Nessler's reagent, potassium tetraiodomercurate(II) () is still occasionally used to test for ammonia owing to its tendency to form the deeply colored iodide salt of Millon's base. Mercury(II) fulminate, Mercury fulminate is a detonator widely used in explosives.


Organomercury compounds

Organic mercury chemical compound, 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 pollution, polluted water. 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.


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 (naturalist), James Lind. The first edition of the Merck's Manual (1899) featured many mercuric compounds such as: * Mercauro * Mercuro-iodo-hemol. * Mercury-ammonium chloride * Mercury Benzoate * Mercuric * Mercury Bichloride (Corrosive Mercuric Chloride, U.S.P.) * Mercury Chloride * Mild Mercury Cyanide * Mercury Succinimide * Mercury Iodide * Red Mercury Biniodide * Mercury Iodide * Yellow Mercury Proto-iodide * Black (Hahnemann), Soluble Mercury Oxide * Red Mercury Oxide * Yellow Mercury Oxide * Mercury Salicylate * Mercury Succinimide * Mercury Imido-succinate * Mercury Sulphate * Basic Mercury Subsulphate; Turpeth Mineral * Mercury Tannate * Mercury-Ammonium Chloride Mercury is an ingredient in amalgam (dentistry), 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. Thiomersal is metabolized to ethyl mercury. Although it was Thiomersal controversy, widely speculated that this mercury-based preservative could cause or trigger autism in children, scientific studies showed no evidence supporting any such link. 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. 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. Today, the use of mercury in medicine has greatly declined in all respects, especially in developed countries. Mercury-in-glass thermometer, Thermometers and
sphygmomanometer A sphygmomanometer ( ), also known as a blood pressure monitor, or blood pressure gauge, is a device used to measure blood pressure, composed of an inflatable cuff to collapse and then release the artery under the cuff in a controlled manner, and ...

sphygmomanometer
s 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 Medical prescription, non-prescription mercury thermometers. In 2003, Washington (U.S. state), Washington and Maine became the first states to ban mercury blood pressure devices. Mercury compounds are found in some over-the-counter drugs, including topical antiseptics, stimulant laxatives, diaper rash, diaper-rash ointment, eye drops, and nasal sprays. The Food and Drug Administration, FDA has "inadequate data to establish general recognition of the safety and effectiveness" of the mercury ingredients in these products. 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 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 (chemistry), amalgam at a cathode made from mercury; this sodium is then reacted with water to produce sodium hydroxide. Many of the industrial mercury releases of the 20th century came from this process, although modern plants claimed to be safe in this regard. After about 1985, all new chloralkali production facilities that were built in the United States used Sodium hydroxide#Methods of production, membrane cell or diaphragm cell technologies to produce chlorine.


Laboratory uses

Some Mercury-in-glass thermometer, 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. Some Meridian circle#Structure, 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. Liquid mercury is a part of popular secondary reference electrode (called the Mercury(I) chloride, 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. 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). In polarography both the dropping mercury electrode and the hanging mercury drop electrode 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 crystallization, 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 lamp A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor that uses to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet light that then causes a coating ...

fluorescent lamp
s. 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. Gaseous mercury is also found in some Gas filled tube, electron tubes, including ignitrons, thyratrons, and mercury arc rectifiers. It is also used in specialist medical care lamps for skin tanning and disinfection. 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 Neon sign#Bombardment, 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. File:Germicidal UV discharge tube glow rotate.jpg, The deep violet glow of a mercury vapor discharge in a germicidal lamp, whose spectrum is rich in invisible ultraviolet radiation. File:Mercuryvaporlamp.jpg, Skin tanner containing a low-pressure mercury vapor lamp and two infrared lamps, which act both as light source and electrical ballast File:Leuchtstofflampen-chtaube050409.jpg, Assorted types of fluorescent lamps. File:Deep Space Atomic Clock-DSAC.jpg, 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.


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. 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.


Firearms

Mercury(II) fulminate is a primary explosive which is mainly used as a Primer (firearm)#Internal priming, primer of a Cartridge (firearms), 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 have been recovered from elite Maya civilization, Maya tombs (100–700 AD) or ritual caches at six sites. This mercury may have been used in bowls as Mirrors in Mesoamerican culture, mirrors for Divination, divinatory purposes. Five of these date to the Classic Period of Maya civilization (c. 250–900) but one example predated this. * 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 Exposition Internationale des Arts et Techniques dans la Vie Moderne (1937), 1937 World Exhibition in Paris. The fountain is now on display at the Fundació Joan Miró in Barcelona. * Mercury was used inside wobbler (fishing), 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. * Mercury
sphygmomanometer A sphygmomanometer ( ), also known as a blood pressure monitor, or blood pressure gauge, is a device used to measure blood pressure, composed of an inflatable cuff to collapse and then release the artery under the cuff in a controlled manner, and ...

sphygmomanometer
s (blood pressure meter),
barometer A barometer is a scientific instrument that is used to measure air pressure in a certain environment. Pressure tendency can forecast short term changes in the weather. Many measurements of air pressure are used within surface weather analysis to ...

barometer
s, diffusion pumps, Mercury coulometer, coulometers, and many other laboratory instruments took advantage of mercury's properties as a very dense, opaque liquid with a nearly linear thermal expansion. * As an electrically conductive liquid, it was used in
mercury switch A mercury switch is an electrical switch In electrical engineering Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems which use electricity, electronic ...

mercury switch
es (including Light switch#Mercury switch, home mercury light switches installed prior to 1970), tilt switches used in old fire detectors, and tilt switches in some home thermostats. * Owing to its acoustic properties, mercury was used as the propagation medium in Delay-line memory#Mercury delay lines, 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. The South Meadow power plant in Hartford, CT employed mercury as its working fluid, in a Binary cycle power plant, 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 fluid, supercritical steam plants in later years. * 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. * Mercury was a propellant for early ion engines in Electrically powered spacecraft propulsion, 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 Colloquially, room temperature is the range of air temperature Temperature is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy, present in all matter, which is the source of the occurrence of heat ...
. 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 Caesium (IUPAC spelling) (American and British English spelling differences, also spelled cesium in American English) is a chemical element with the Symbol (chemistry), symbol Cs and atomic number 55. It is a soft, silvery-golden alkali ...

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 The noble gases (historically also the inert gases; sometimes referred to as aerogens) make up a class of chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that m ...
nature, and has a high liquid density under mild cryogenic storage. Other applications made use of the chemical properties of mercury: * The mercury battery is a non-rechargeable Electrochemical cell, 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. * 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 syphilis, antisyphilitics. * It was allegedly used by Allies of World War II, allied spies to sabotage Luftwaffe planes: a mercury paste was applied to bare
aluminium Aluminium (aluminum in and ) is a with the  Al and  13. Aluminium has a density lower than those of other common , at approximately one third that of . It has a great affinity towards , and of on the surface when exposed to air ...

aluminium
, causing the metal to rapidly Corrosion, corrode; this would cause structural failures. * 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. * As electrodes in some types of electrolysis, battery (electricity), batteries (mercury battery, mercury cells), sodium hydroxide and chlorine production, handheld games, catalysts, insecticides. * Mercury was once used as a gun barrel bore cleaner. * 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. 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. * Gold and silver mining. Historically, mercury was used extensively in hydraulic mining, 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. 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. Mercury was also used in silver mining.


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. 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. 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.


Toxicity and safety

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 mercury-in-glass thermometer, thermometers or fluorescent light bulbs), specific cleaning procedures are used to avoid exposure and contain the spill. 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 Sulfur (in nontechnical British English: sulphur) is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: th ...

sulfur
,
zinc Zinc is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

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 Methylmercury (sometimes methyl mercury) is an extremely toxic organometallic cation An ion () is a particle, atom or molecule with a net electric charge, electrical charge. The charge of the electron is considered negative by convention ...

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. 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: * 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. * 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. * 6.8% from non-ferrous metal production, typically smelters. * 6.4% from cement production. * 3.0% from waste disposal, including municipal waste, 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. 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. 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. Permafrost soils have accumulated mercury through atmospheric deposition, and permafrost thaw in Cryosphere, cryospheric regions is also a mechanism of mercury release into lakes, rivers, and wetlands. Mercury also enters into the environment through the improper disposal (e.g., land filling, incineration) of certain products. Products containing mercury include: auto parts, battery (electricity), batteries, fluorescent bulbs, medical products, thermometers, and thermostats. Due to health concerns (see below), waste management, 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. Most thermometers now use pigmented
alcohol In chemistry, alcohol is an organic compound that carries at least one hydroxyl functional group (−OH) bound to a Saturated and unsaturated compounds, saturated carbon atom. The term alcohol originally referred to the primary alcohol ethan ...

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 Isotopes of lithium, 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. A serious industrial disasters, industrial disaster was the dumping of mercury compounds into Minamata Bay, Japan. It is estimated that over 3,000 people suffered various deformities, severe mercury poisoning symptoms or death from what became known as Minamata disease. 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. While mercury is a constituent of tobacco smoke, 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.


Sediment contamination

Sediments within large urban-industrial estuaries act as an important sink for point source and diffuse mercury pollution within catchments. 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). 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. 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. 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.


Occupational exposure

Due to the health effects of mercury exposure, industrial and commercial uses are regulated in many countries. The World Health Organization, Occupational Safety and Health Administration, OSHA, and National Institute for Occupational Safety and Health, 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 Methylmercury (sometimes methyl mercury) is an extremely toxic organometallic cation An ion () is a particle, atom or molecule with a net electric charge, electrical charge. The charge of the electron is considered negative by convention ...

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. Mercury presence in fish muscles can be studied using non-lethal muscle Biopsy, biopsies. 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 Mercury poisoning is a type of metal poisoning due to exposure to mercury. Symptoms depend upon the type, dose, method, and duration of exposure. They may include muscle weakness, poor coordination, numbness in the hands and feet, skin rashes, ...
happened this way in Minamata, Kumamoto, 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.


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. 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. 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.


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. 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.


Regulations


International

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


United States

In the United States, the United States Environmental Protection Agency, Environmental Protection Agency is charged with regulating and managing mercury contamination. Several laws give the EPA this authority, including the Clean Air Act (United States), 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. North America contributed approximately 11% of the total global anthropogenic mercury emissions in 1995. The United States Clean Air Act (1990), 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 that added power plants to the list of sources that should be controlled and instituted a national emissions trading, 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. 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. The EPA announced new rules for coal-fired power plants on 22 December 2011. 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.


European Union

In the European Union, the directive on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment (see Restriction of Hazardous Substances Directive, RoHS) bans mercury from certain electrical and electronic products, and limits the amount of mercury in other products to less than 1000 Parts per million, ppm. Article 4 Paragraph 1. e.g. "Member States shall ensure that, from July 1, 2006, new electrical and electronic equipment put on the market does not contain lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB) or polybrominated diphenyl ethers (PBDE)." There are restrictions for mercury concentration in packaging (the limit is 100 ppm for sum of mercury, lead, hexavalent chromium and
cadmium Cadmium is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical eleme ...

cadmium
) and batteries (the limit is 5 ppm). In July 2007, the European Union also banned mercury in non-electrical measuring devices, such as
thermometer (mercury-in-glass thermometer) for measurement of room temperature. A thermometer is a device that temperature measurement, measures temperature or a temperature gradient A temperature gradient is a physical quantity that describes in which dir ...

thermometer
s and
barometer A barometer is a scientific instrument that is used to measure air pressure in a certain environment. Pressure tendency can forecast short term changes in the weather. Many measurements of air pressure are used within surface weather analysis to ...

barometer
s. 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.


Norway

Norway enacted a total ban on the use of mercury in the manufacturing and import/export of mercury products, effective 1 January 2008. 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. 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."Edlich, Richard F.; Rhoads, Samantha K.; Cantrell, Holly S.; Azavedo, Sabrina M. and Newkirk, Anthony T
Banning Mercury Amalgam
. US FDA


Sweden

Products containing mercury were banned in Sweden in 2009.


Denmark

In 2008, Denmark also banned dental mercury amalgam, except for Molar (tooth), molar masticating surface fillings in permanent (adult) teeth.


See also

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


References


Further reading

* Andrew Scott Johnston, ''Mercury and the Making of California: Mining, Landscape, and Race, 1840–1890.'' Boulder, CO: University Press of Colorado, 2013.


External links


Chemistry in its element podcast
(MP3) from the Royal Society of Chemistry's Chemistry World
Mercury


at ''The Periodic Table of Videos'' (University of Nottingham)
Centers for Disease Control and Prevention – Mercury Topic







Stopping Pollution: Mercury
– Oceana
Natural Resources Defense Council (NRDC): Mercury Contamination in Fish guide
– Natural Resources Defense Council, 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.
* {{DEFAULTSORT:Mercury Mercury (element), Chemical elements Coolants Endocrine disruptors Native element minerals Neurotoxins Nuclear reactor coolants Occupational safety and health Transition metals Chemical elements with rhombohedral structure