Mercury is a
chemical element
A chemical element is a species of atoms that have a given number of protons in their nuclei, including the pure substance consisting only of that species. Unlike chemical compounds, chemical elements cannot be broken down into simpler sub ...
with the
symbol Hg and
atomic number
The atomic number or nuclear charge number (symbol ''Z'') of a chemical element is the charge number of an atomic nucleus. For ordinary nuclei, this is equal to the proton number (''n''p) or the number of protons found in the nucleus of every ...
80. It is also known as quicksilver and was formerly named hydrargyrum ( ) from the Greek words, ''hydor'' (water) and ''argyros'' (silver). 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
* Heavy, ...
, silvery
d-block
A block of the periodic table is a set of elements unified by the atomic orbitals their valence electrons or vacancies lie in. The term appears to have been first used by Charles Janet. Each block is named after its characteristic orbital: s-blo ...
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
Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table ( halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simi ...
, though metals such as
caesium,
gallium, and
rubidium melt just above
room temperature.
Mercury occurs in deposits throughout the world mostly as
cinnabar
Cinnabar (), or cinnabarite (), 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 source for the bri ...
(
mercuric sulfide
Mercury sulfide, or mercury(II) sulfide is a chemical compound composed of the chemical elements mercury and sulfur. It is represented by the chemical formula HgS. It is virtually insoluble in water.
Crystal structure
HgS is dimorphic with ...
). The red pigment
vermilion
Vermilion (sometimes vermillion) is a color, color family, and pigment most often made, since antiquity until the 19th century, from the powdered mineral cinnabar (a form of mercury sulfide, which is toxic) and its corresponding color. It i ...
is obtained by
grinding
Grind is the cross-sectional shape of a blade.
Grind, grinds, or grinding may also refer to:
Grinding action
* Grinding (abrasive cutting), a method of crafting
* Grinding (dance), suggestive club dancing
* Grinding (video gaming), repetitive and ...
natural cinnabar or synthetic mercuric sulfide.
Mercury is used in
thermometer
A thermometer is a device that measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a mercury-in-glass 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 ...
s,
manometer
Pressure measurement is the measurement of an applied force by a fluid (liquid or gas) on a surface. Pressure is typically measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressu ...
s,
sphygmomanometer
A sphygmomanometer ( ), 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 a mercury ...
s,
float valve
A ballcock (also balltap or float valve) is a mechanism or machine for filling water tanks, such as those found in flush toilets, while avoiding overflow and (in the event of low water pressure) backflow. The modern ballcock was invented by J ...
s,
mercury switch
A mercury switch is an electrical switch that opens and closes a circuit when a small amount of the liquid metal mercury connects metal electrodes to close the circuit. There are several different basic designs (tilt, displacement, radial, etc ...
es,
mercury relay
A mercury relay (mercury displacement relay, mercury contactor) is a relay that uses mercury as the switching element.
They are used as high-current switches or contactors, where contact erosion from constant cycling would be a problem for conven ...
s,
fluorescent lamp
A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet ligh ...
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- or
galinstan-filled glass thermometers and
thermistor
A thermistor is a type of resistor whose resistance is strongly dependent on temperature, more so than in standard resistors. The word thermistor is a portmanteau of ''thermal'' and ''resistor''.
Thermistors are divided based on their conduction ...
- or
infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
-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
Amalgam most commonly refers to:
* Amalgam (chemistry), mercury alloy
* Amalgam (dentistry), material of silver tooth fillings
** Bonded amalgam, used in dentistry
Amalgam may also refer to:
* Amalgam Comics, a publisher
* Amalgam Digital
...
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 caries or external trauma as well as to the replacement of such structure sup ...
in some locales. It is also used in
fluorescent lighting
A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet ligh ...
. Electricity passed through mercury vapor in a fluorescent lamp produces short-wave
ultraviolet light
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...
, which then causes the phosphor in the tube to
fluoresce
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, tha ...
, making visible light.
Mercury poisoning can result from exposure to water-soluble forms of mercury (such as
mercuric chloride
Mercury(II) chloride (or mercury bichloride, mercury dichloride), historically also known as sulema or corrosive sublimate, is the inorganic chemical compound of mercury and chlorine with the formula HgCl2. It is white crystalline solid and is a ...
or
methylmercury), by inhalation of mercury vapor, or by ingesting any form of mercury.
Properties
Physical properties
![Pound-coin-floating-in-mercury](https://upload.wikimedia.org/wikipedia/commons/5/55/Pound-coin-floating-in-mercury.jpg)
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.
[ in ]
It has a
freezing point
The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depend ...
of −38.83 °C and a
boiling point of 356.73 °C,
both the lowest of any stable metal, although preliminary experiments on
copernicium
Copernicium is a synthetic chemical element with the symbol Cn and atomic number 112. Its known isotopes are extremely radioactive, and have only been created in a laboratory. The most stable known isotope, copernicium-285, has a half-life of ap ...
and
flerovium
Flerovium is a Transactinide element, superheavy chemical element with Chemical symbol, symbol Fl and atomic number 114. It is an extremely radioactive synthetic element. It is named after the Flerov Laboratory of Nuclear Reactions of the Joint ...
have indicated that they have even lower boiling points. This effect is due to
lanthanide contraction
The lanthanide contraction is the greater-than-expected decrease in atomic radii/ionic radii of the elements in the lanthanide series from atomic number 57, lanthanum, to 71, lutetium, which results in smaller than otherwise expected atomic radii ...
and
relativistic contraction reducing the radius of the outermost electrons, and thus weakening the metallic bonding in mercury.
Upon freezing, the volume of mercury decreases by 3.59% and its density changes from 13.69 g/cm
3 when liquid to 14.184 g/cm
3 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.
Table of thermal and physical properties of liquid mercury:
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
Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...
or
aqua regia dissolve it to give
sulfate
The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...
,
nitrate, and
chloride
The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the element chlorine (a halogen) gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride sa ...
. 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).
Amalgams
![Mercury discharge tube](https://upload.wikimedia.org/wikipedia/commons/9/95/Mercury_discharge_tube.jpg)
Mercury dissolves many metals such as
gold
Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile me ...
and
silver
Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...
to form
amalgams.
Iron
Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...
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 with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...
,
copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
and
zinc
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
are also resistant in forming amalgams. Other elements that do not readily form amalgams with mercury include
platinum
Platinum is a chemical element with the symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish , a diminutive of "silver".
Pla ...
.
Sodium amalgam
Sodium amalgam, commonly denoted Na(Hg), is an alloy of mercury and sodium. The term amalgam is used for alloys, intermetallic compounds, and solutions (both solid solutions and liquid solutions) involving mercury as a major component. Sodium am ...
is a common reducing agent in
organic synthesis, and is also used in
high-pressure sodium lamps.
Mercury readily combines with
aluminium
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
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
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 iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO( ...
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 (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numb ...
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 that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...
s are with a
half-life
Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable at ...
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 in which nuclei in a strong constant magnetic field are perturbed by a weak oscillating magnetic field (in the near field) and respond by producing an electromagnetic signal with ...
-active nuclei, having spins of and respectively.
For the
synthesis of precious metals two stable mercury isotopes are of potential interest - the trace isotope and the more abundant . Both are "one neutron removed" from , a radioisotope which decays to , the only known stable isotope of gold. However, the rarity of and the high energy requirements of
nuclear reaction
In nuclear physics and nuclear chemistry, a nuclear reaction is a process in which two nuclei, or a nucleus and an external subatomic particle, collide to produce one or more new nuclides. Thus, a nuclear reaction must cause a transformatio ...
s "knocking out" a neutron from (either via
photodisintegration
Photodisintegration (also called phototransmutation, or a photonuclear reaction) is a nuclear process in which an atomic nucleus absorbs a high-energy gamma ray, enters an excited state, and immediately decays by emitting a subatomic particle. The ...
or via a (n,2n) reaction involving
fast neutron
The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term ''temperature'' is used, since hot, thermal and cold neutrons are moderated in a medium with ...
s), have thus far ruled out practical application of this "real philosopher's stone".
Etymology
![Mercury symbol (fixed width)](https://upload.wikimedia.org/wikipedia/commons/b/bb/Mercury_symbol_%28fixed_width%29.svg)
"Hg" is the modern
chemical symbol
Chemical symbols are the abbreviations used in chemistry for chemical elements, functional groups and chemical compounds. Element symbols for chemical elements normally consist of one or two letters from the Latin alphabet and are written with ...
for mercury. It is an abbreviation of , a
romanized form of the
ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...
name for mercury, (). is a Greek compound word meaning "water-silver", from - (-), the root of () "water", and () "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
Alchemy (from Arabic: ''al-kīmiyā''; from Ancient Greek: χυμεία, ''khumeía'') is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practiced in China, India, the Muslim world, ...
, the seven known metals—quicksilver,
gold
Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile me ...
,
silver
Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...
,
copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
,
iron
Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...
,
lead
Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
, and
tin
Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal.
Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...
—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 symbol
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 symbol varied between alchemists, so this pag ...
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 ...
tombs that date from 1500 BC.
In
China and
Tibet
Tibet (; ''Böd''; ) is a region in East Asia, covering much of the Tibetan Plateau and spanning about . It is the traditional homeland of the Tibetan people. Also resident on the plateau are some other ethnic groups such as Monpa, Taman ...
, 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 ''immureme ...
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 Qin 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 Emp ...
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, Ahmad ibn Tulun. His father, the autonomous ruler o ...
, the second
Tulunid
The Tulunids (), were a Mamluk dynasty of Turkic origin who were the first independent dynasty to rule Egypt, as well as much of Syria, since the Ptolemaic dynasty. They were independent from 868, when they broke away from the central authority ...
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 "
Temple of the Feathered Serpent," "the third largest pyramid of
Teotihuacan
Teotihuacan (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 known today as t ...
," Mexico along with "jade statues, jaguar remains, a box filled with carved shells and rubber balls".
Aristotle
Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of ph ...
recounts that
Daedalus
In Greek mythology, Daedalus (, ; Greek: Δαίδαλος; Latin: ''Daedalus''; Etruscan: ''Taitale'') was a skillful architect and craftsman, seen as a symbol of wisdom, knowledge and power. He is the father of Icarus, the uncle of Perdix, a ...
made a wooden statue of
Venus
Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never f ...
move by pouring quicksilver in its interior. In
Greek mythology
A major branch of classical mythology, Greek mythology is the body of myths originally told by the ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the origin and nature of the world, the lives and activities ...
Daedalus gave the appearance of voice in his statues using quicksilver. The
ancient Greeks
Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cult ...
used
cinnabar
Cinnabar (), or cinnabarite (), 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 source for the bri ...
(mercury sulfide) in ointments; the
ancient Egyptians and the
Romans
Roman or Romans most often refers to:
*Rome, the capital city of Italy
* Ancient Rome, Roman civilization from 8th century BC to 5th century AD
*Roman people, the people of ancient Rome
*''Epistle to the Romans'', shortened to ''Romans'', a lette ...
used it in
cosmetics
Cosmetics are constituted mixtures of chemical compounds derived from either natural sources, or synthetically created ones. Cosmetics have various purposes. Those designed for personal care and skin care can be used to cleanse or protect ...
. In
Lamanai
Lamanai (from ''Lama'anayin'', "submerged crocodile" in Yucatec Maya) is a Mesoamerican archaeological site, and was once a major city of the Maya civilization, located in the north of Belize, in Orange Walk District. The site's name is pre-Columb ...
, once a major city of the
Maya civilization
The Maya civilization () of the Mesoamerican people is known by its ancient temples and glyphs. Its Maya script is the most sophisticated and highly developed writing system in the pre-Columbian Americas. It is also noted for its art, a ...
, a pool of mercury was found under a marker in a
Mesoamerican ballcourt
A Mesoamerican ballcourt ( nah, tlachtli) 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 i ...
. By 500 BC mercury was used to make
amalgams (Medieval Latin ''amalgama'', "alloy of mercury") with other metals.
Alchemists
Alchemy (from Arabic: ''al-kīmiyā''; from Ancient Greek: χυμεία, ''khumeía'') is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practiced in China, India, the Muslim world, ...
thought of mercury as the
First Matter from which all metals were formed. They believed that different
metals
A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typical ...
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.
The mines in
Almadén
Almadén () is a town and municipality in the Spanish province of Ciudad Real, within the autonomous community of Castile-La Mancha. The town is located at 4° 49' W and 38° 46' N and is 589 meters above sea level. Almadén is approximately 3 ...
(Spain),
Monte Amiata
Mount Amiata is the largest of the lava domes in the Amiata lava dome complex located about 20 km northwest of Lake Bolsena in the southern Tuscany region of Italy. It is located within the provinces of Grosseto and Siena.
Geology
Mount Am ...
(Italy), and
Idrija
Idrija (, in older sources ''Zgornja Idrija''; german: (Ober)idria, it, Idria) is a town in western Slovenia. It is the seat of the Municipality of Idrija. It is located in the traditional region of Inner Carniola and is in the Gorizia Statisti ...
(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 (rare) or in
cinnabar
Cinnabar (), or cinnabarite (), 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 source for the bri ...
, metacinnabar,
sphalerite,
corderoite
Corderoite is an extremely rare mercury sulfide chloride mineral with formula Hg3S2Cl2. It crystallizes in the isometric crystal system. It is soft, 1.5 to 2 on the Mohs scale, and varies in color from light gray to black and rarely pink or yell ...
,
livingstonite and other
mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...
s, with cinnabar (HgS) being the most common ore.
Mercury ores often occur in hot springs or other
volcanic
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
On Earth, volcanoes are most often found where tectonic plates a ...
regions.
Beginning in 1558, with the invention of the
patio process
The patio process is a process for extracting silver from ore. Smelting, or refining, was necessary because silver does not occur by itself in a natural state like some metals. Instead, it is made up of a larger ore body. Thus, smelting, or refin ...
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
, image_flag = Flag of Peru.svg
, image_coat = Escudo nacional del Perú.svg
, other_symbol = Great Seal of the State
, other_symbol_type = National seal
, national_motto = "Firm and Happy f ...
. 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
Huancavelica () or Wankawillka in Quechua is a city in Peru. It is the capital of the department of Huancavelica and according to the 2017 census had a population of 49,570 people. The city was established on August 5, 1572 by the Viceroy ...
, Peru, over the course of three centuries following the discovery of deposits there in 1563. The patio process and later
pan amalgamation The pan amalgamation process is a method to extract silver from ore, using salt and copper(II) sulfate in addition to mercury. The process was widely used from 1609 through the 19th century; it is no longer used.
The patio process had been used t ...
process continued to create great demand for mercury to treat silver ores until the late 19th century.
![Mercury-27128](https://upload.wikimedia.org/wikipedia/commons/7/74/Mercury-27128.jpg)
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. It is the seat of the Municipality of Idrija. It is located in the traditional region of Inner Carniola and is in the Gorizia Statisti ...
) and Spain (
Almadén
Almadén () is a town and municipality in the Spanish province of Ciudad Real, within the autonomous community of Castile-La Mancha. The town is located at 4° 49' W and 38° 46' N and is 589 meters above sea level. Almadén is approximately 3 ...
), shut down due to the fall of the price of mercury.
Nevada
Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...
'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
Flask may refer to:
Container
* Hip flask, a small container used to carry a small amount of liquid
* Laboratory flask, laboratory glassware for holding larger volumes than simple test tubes
** Erlenmeyer flask, a common laboratory flask wit ...
.
Mercury is extracted by heating cinnabar in a current of air and condensing the vapor. The equation for this extraction is
:HgS + O
2 → Hg + SO
2
In 2005, China was the top producer of mercury with almost two-thirds global share followed by
Kyrgyzstan
Kyrgyzstan,, pronounced or the Kyrgyz Republic, is a landlocked country in Central Asia. Kyrgyzstan is bordered by Kazakhstan to the north, Uzbekistan to the west, Tajikistan to the south, and the People's Republic of China to the ea ...
. 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
The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been de ...
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
Guangzhou (, ; ; or ; ), also known as Canton () and alternatively romanized as Kwongchow or Kwangchow, is the capital and largest city of Guangdong province in southern China. Located on the Pearl River about north-northwest of Hong Kon ...
, and in
Guizhou
Guizhou (; formerly Kweichow) is a landlocked province in the southwest region of the People's Republic of China. Its capital and largest city is Guiyang, in the center of the province. Guizhou borders the autonomous region of Guangxi to the ...
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
Santa Clara County, officially the County of Santa Clara, is the sixth-most populous county in the U.S. state of California, with a population of 1,936,259, as of the 2020 census. Santa Clara County and neighboring San Benito County together ...
purchased the historic
Almaden Quicksilver Mine and created a county park on the site, after conducting extensive safety and environmental analysis of the property.
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.
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
Diamagnetic materials are repelled by a magnetic field; an applied magnetic field creates an induced magnetic field in them in the opposite direction, causing a repulsive force. In contrast, paramagnetic and ferromagnetic materials are attracted ...
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
Mercury(I) chloride is the chemical compound with the formula Hg2Cl2. Also known as the mineral calomel (a rare mineral) or mercurous chloride, this dense white or yellowish-white, odorless solid is the principal example of a mercury(I) compound ...
, a colorless solid also known as
calomel
Calomel is a mercury chloride mineral with formula Hg2Cl2 (see mercury(I) chloride). The name derives from Greek ''kalos'' (beautiful) and ''melas'' (black) because it turns black on reaction with ammonia. This was known to alchemists.
Calomel ...
, is really the compound with the formula Hg
2Cl
2, 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
Mercury(II) chloride (or mercury bichloride, mercury dichloride), historically also known as sulema or corrosive sublimate, is the inorganic chemical compound of mercury and chlorine with the formula HgCl2. It is white crystalline solid and is ...
, an easily
sublimating white solid. HgCl
2 forms
coordination complex
A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as '' ligands'' or complexing agents. ...
es that are typically tetrahedral, e.g. .
Mercury(II) oxide
Mercury(II) oxide, also called mercuric oxide or simply mercury oxide, is the inorganic compound with the formula Hg O. It has a red or orange color. Mercury(II) oxide is a solid at room temperature and pressure. The mineral form montroydite is v ...
, 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
Joseph Priestley (; 24 March 1733 – 6 February 1804) was an English chemist, natural philosopher, separatist theologian, grammarian, multi-subject educator, and liberal political theorist. He published over 150 works, and conducted exp ...
in an early synthesis of pure
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
.
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
The chalcogens (ore forming) ( ) are the chemical elements in group 16 of the periodic table. This group is also known as the oxygen family. Group 16 consists of the elements oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and the radioa ...
. Preeminent is
mercury(II) sulfide
Mercury sulfide, or mercury(II) sulfide is a chemical compound composed of the chemical elements mercury (element), mercury and sulfur. It is represented by the chemical formula HgS. It is virtually insoluble in water.
Crystal structure
HgS ...
, HgS, which occurs in nature as the ore
cinnabar
Cinnabar (), or cinnabarite (), 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 source for the bri ...
and is the brilliant pigment
vermillion
Vermilion (sometimes vermillion) is a color, color family, and pigment most often made, since antiquity until the 19th century, from the powdered mineral cinnabar (a form of mercury sulfide, which is toxic) and its corresponding color. It is v ...
. Like ZnS, HgS crystallizes in two
forms
Form is the shape, visual appearance, or configuration of an object. In a wider sense, the form is the way something happens.
Form also refers to:
*Form (document), a document (printed or electronic) with spaces in which to write or enter data
* ...
, the reddish cubic form and the black
zinc blende
Sphalerite (sometimes spelled sphaelerite) is a sulfide mineral with the chemical formula . It is the most important ore of zinc. Sphalerite is found in a variety of deposit types, but it is primarily in sedimentary exhalative, Mississippi-Va ...
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 Hg1−xCdxTe or mercury cadmium telluride (also cadmium mercury telluride, MCT, MerCad Telluride, MerCadTel, MerCaT or CMT) is a chemical compound of cadmium telluride (CdTe) and mercury telluride (HgTe) with a tunable bandgap spanning the shortwav ...
and
mercury zinc telluride being
semiconductors useful as
infrared detector
An infrared detector is a detector that reacts to infrared (IR) radiation. The two main types of detectors are thermal and photonic (photodetectors).
The thermal effects of the incident IR radiation can be followed through many temperature depen ...
materials.
Mercury(II) salts form a variety of complex derivatives with
ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...
. These include Millon's base (Hg
2N
+), the one-dimensional polymer (salts of )), and "fusible white precipitate" or
3)2">g(NH3)2l
2. Known as
Nessler's reagent,
potassium tetraiodomercurate(II)
Potassium tetraiodomercurate(II) is an inorganic compound consisting of potassium cations and the tetraiodomercurate(II) anion. It is mainly used as Nessler's reagent, a 0.09 mol/L solution of potassium tetraiodomercurate(II) (K2 gI4 in 2.5&n ...
() 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
Mercury(II) fulminate, or Hg(CNO)2, is a primary explosive. It is highly sensitive to friction, heat and shock and is mainly used as a trigger for other explosives in percussion caps and detonators. Mercury(II) cyanate, though its chemical formu ...
is a
detonator widely used in
explosives.
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
An organocadmium compound is an organometallic compound containing a carbon to cadmium chemical bond. Organocadmium chemistry describes physical properties, synthesis, reactions and use of these compounds. Cadmium shares group 12 with zinc and me ...
and
organozinc
Organozinc compounds in organic chemistry contain carbon (C) to zinc (Zn) chemical bonds. Organozinc chemistry is the science of organozinc compounds describing their physical properties, synthesis and reactions.The Chemistry of Organozinc Compoun ...
compounds, organomercury compounds do not react with water. They usually have the formula HgR
2, which are often volatile, or HgRX, which are often solids, where R is
aryl
In organic chemistry, an aryl is any functional group or substituent derived from an aromaticity, aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar ...
or
alkyl
In organic chemistry, an alkyl group is an alkane missing one hydrogen.
The term ''alkyl'' is intentionally unspecific to include many possible substitutions.
An acyclic alkyl has the general formula of . A cycloalkyl is derived from a cycloa ...
and X is usually halide or acetate.
Methylmercury, a generic term for compounds with the formula CH
3HgX, is a dangerous family of compounds that are often found in
polluted
Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...
water.
They arise by a process known as
biomethylation
In the chemical sciences, methylation denotes the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These ...
.
Applications
![Maximum thermometer close up 2](https://upload.wikimedia.org/wikipedia/commons/d/d0/Maximum_thermometer_close_up_2.JPG)
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
A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet ligh ...
, 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
An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductilit ...
.
Medicine
![Amalgam](https://upload.wikimedia.org/wikipedia/commons/3/37/Amalgam.jpg)
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
James Lind (4 October 1716 – 13 July 1794) was a Scottish doctor. He was a pioneer of naval hygiene in the Royal Navy. By conducting one of the first ever clinical trials, he developed the theory that citrus fruits cured scurvy.
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
dental amalgams.
Thiomersal
Thiomersal (INN), or thimerosal (USAN, JAN), is an organomercury compound. It is a well-established antiseptic and antifungal agent.
The pharmaceutical corporation Eli Lilly and Company gave thiomersal the trade name Merthiolate. It has been u ...
(called ''Thimerosal'' in the United States) is an
organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. T ...
used as a
preservative
A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or by ...
in
vaccine
A vaccine is a biological preparation that provides active acquired immunity to a particular infectious or malignant disease. The safety and effectiveness of vaccines has been widely studied and verified. s, though this use is in decline. 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. 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
Merbromin (marketed as Mercurochrome, Merbromine, Mercurocol, Sodium mercurescein, Asceptichrome, Supercrome, Brocasept and Cinfacromin) is an organomercuric disodium salt compound used as a topical antiseptic for minor cuts and scrapes and a ...
(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
Traditional Chinese medicine (TCM) is an alternative medical practice drawn from traditional medicine in China. It has been described as "fraught with pseudoscience", with the majority of its treatments having no logical mechanism of acti ...
. 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 ( ), 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 a mercury ...
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 (H
2) 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#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
Mercury(II) chloride (or mercury bichloride, mercury dichloride), historically also known as sulema or corrosive sublimate, is the inorganic chemical compound of mercury and chlorine with the formula HgCl2. It is white crystalline solid and is ...
or
potassium tetraiodomercurate(II)
Potassium tetraiodomercurate(II) is an inorganic compound consisting of potassium cations and the tetraiodomercurate(II) anion. It is mainly used as Nessler's reagent, a 0.09 mol/L solution of potassium tetraiodomercurate(II) (K2 gI4 in 2.5&n ...
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 gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet ligh ...
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.
Skin whitening
Mercury is effective as an active ingredient in skin whitening compounds used to depigment skin. 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.
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
![Barometer mercury column hg](https://upload.wikimedia.org/wikipedia/commons/b/b9/Barometer_mercury_column_hg.jpg)
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 ( ), 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 a mercury ...
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 ...
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 that opens and closes a circuit when a small amount of the liquid metal mercury connects metal electrodes to close the circuit. There are several different basic designs (tilt, displacement, radial, etc ...
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. 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.
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 American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
, 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(NO
3)
2·2H
2O. 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
Mercury(I) chloride is the chemical compound with the formula Hg2Cl2. Also known as the mineral calomel (a rare mineral) or mercurous chloride, this dense white or yellowish-white, odorless solid is the principal example of a mercury(I) compound ...
(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
Merbromin (marketed as Mercurochrome, Merbromine, Mercurocol, Sodium mercurescein, Asceptichrome, Supercrome, Brocasept and Cinfacromin) is an organomercuric disodium salt compound used as a topical antiseptic for minor cuts and scrapes and a ...
(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,
zinc
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
, 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
![Mercury in Ice Core Upper Fremont Glacier](https://upload.wikimedia.org/wikipedia/commons/1/12/Mercury_in_Ice_Core_Upper_Fremont_Glacier.svg)
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/m
3. 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/m
3. The average was 0.069 μg/m
3.
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 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 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.
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
![EPA workers clean up residential mercury spill (3986684199)](https://upload.wikimedia.org/wikipedia/commons/7/79/EPA_workers_clean_up_residential_mercury_spill_%283986684199%29.jpg)
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, 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 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/m
3.
A study has shown that acute exposure (4–8 hours) to calculated elemental mercury levels of 1.1 to 44 mg/m
3 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 European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been de ...
, 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
Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
, hexavalent chromium and 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
A thermometer is a device that measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a mercury-in-glass 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 ...
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."
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
*
External links
Chemistry in its element podcast(MP3) from the Royal Society of Chemistry's Chemistry World
Mercuryat ''The Periodic Table of Videos'' (University of Nottingham)
Centers for Disease Control and Prevention – Mercury TopicStopping Pollution: Mercury– Oceana
Natural Resources Defense Council (NRDC): Mercury Contamination in Fish guide– Natural Resources Defense Council, NRDC
NLM Hazardous Substances Databank – MercuryBBC – Earth News – Mercury "turns" wetland birds such as ibises homosexualChanging Patterns in the Use, Recycling, and Material Substitution of Mercury in the United StatesUnited 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