Mercury (element)

iso	NA	half-life	DM	DE M eV	DP
¹⁹⁴Hg	{syn.}	444 y	&epsilon	0.040	¹⁹⁴Au
¹⁹⁶Hg	0.15%	Hg is stable with 116 neutrons
¹⁹⁸Hg	9.97%	Hg is stable with 118 neutrons
¹⁹⁹Hg	16.87%	Hg is stable with 119 neutrons
²⁰⁰Hg	23.1%	Hg is stable with 120 neutrons
²⁰¹Hg	13.18%	Hg is stable with 121 neutrons
²⁰²Hg	29.86%	Hg is stable with 122 neutrons
²⁰⁴Hg	6.87%	Hg is stable with 124 neutrons

SI units & STP are used except where noted.

Mercury, also called quicksilver, is a chemical element in the periodic table that has the symbol Hg and atomic number 80. A heavy, silvery, toxic, transition metal, mercury is one of only two elements that are liquid at everyday room-temperatures (the other is Bromine) and is used in thermometers, barometers and other scientific apparatus. Mercury is mostly obtained by reduction from the mineral cinnabar.

Table of contents

1 Notable characteristics
2 Applications
3 History
4 Occurrence
5 Compounds
6 Isotopes
7 Precautions
8 External links

Notable characteristics

Mercury is a heavy, silvery-white univalent and bivalent transition metal that is a relatively poor conductor of heat but a decent conductor of electricity and is the only common metal that is liquid at room temperature (forming an opaque glistening liquid).

Mercury easily forms alloys with almost all common metals, including gold and silver but not iron. Any of these alloys is called an amalgam.

The freezing point of mercury is -40 ° Celsius which is the same as -40 ° Fahrenheit. This is the only point at which these two temperature scales coincide.

This metal also has uniform volumetric thermal expansion, is less reactive than zinc and cadmium and does not displace hydrogen from acids. Common oxidation states of this element are; mercurous, or +1, and mercuric, or +2. Rare instances of +3 mercury compounds exist.

Applications

Most mercury is used for the manufacture of industrial chemicals and for electrical and electronic applications. In addition, mercury is widely used in thermometers, especially ones which are used to measure high temperatures. Other uses;

The ease with which it forms amalgams with gold has resulted in its use in gold recovery from ores.

In addition to thermometers, mercury is used in barometers, diffusion pumps, and many other laboratory instruments.
The triple point of mercury, -38.8344 °C, is a fixed point used as a temperature standard for the International Temperature Scale (ITS-90).
Gaseous mercury is used in mercury-vapor lamps and advertising signs.

Miscellaneous uses; mercury switches, pesticides, dental amalgams/preparations, mercury cells for caustic soda and chlorine production, anti-fouling paint, electrode in some types of electrolysis, batteries (mercury cells), and catalysts.

History

Mercury was known to the ancient Chinese and Hindus and was found in Egyptian tombs that date from 1500s BC. By 500 BC it was used to make amalgams with other metals. The ancient Greekss used this toxic metal in ointments and the Romans used it in cosmetics. Alchemists thought it to be the stuff from which all matter was formed and they also thought that when it hardened it turned into gold.

In the 18th and 19th centuries, mercury nitrate was used to remove fur from the animal skins from which felt hats were made. This caused many cases of brain damage among hatters, or milliners, leading, it is claimed, to the simile "as mad as a hatter", and thereby to the Mad Hatter of Alice in Wonderland fame.

It was named by alchemists after the Roman god Mercury. Its symbol Hg comes from hydrargyrum, a Latinised form of the Greek word hydrargyros, which was a compound word whose Greek roots meant 'water' and 'silver'. Mercury is one of the few elements that has an alchemical symbol. If you have the right browser and font to support Unicode, you should see the symbol here: ☿.

Occurrence

A rare element in the earth's crust, mercury is found either as a native metal (rare) or in cinnabar, corderoite, livingstonite, and other minerals with cinnabar (HgS) being the most common ore. Approximately 50% of the global supply comes from Spain and Italy with much of the rest coming from Yugoslavia, Russia, and North America. The metal is extracted by heating cinnabar in a current of air and by condensing the vapor.

Compounds

The most important salts are:

mercury chloride (which is very corrosive, sublimates and is a violent poison)
mercurous chloride (which is calomel and is sometimes still used in medicine)
mercury fulminate, (a detonator widely used in explosives), and
mercuric sulfide (used to make vermilion which is a high-grade paint pigment).

Organic mercury compoundss are also important. Laboratory test have found that electrical discharge causes the noble gases neon, argon, krypton, and xenon to combine with mercury vapor. The products of this combination are held together with van der Waals forces and result in HgNe, HgAr, HgKr, and HgXe. Methyl mercury is a dangerous compound that is widely found as a pollutant in water bodies and streams.

Isotopes

There are seven stable isotopes of mercury with Hg-202 being the most abundant (26.86%). The longest-lived radioisotopes are Hg-194 with a half-life of 444 years, and Hg-203 with a half-life of 46.612 days. Most of the remaining radioisotopes have half-lifes that are less than a day.

Precautions

Mercury is highly toxic in both liquid and gaseous forms. This is a toxic heavy metal that causes brain and liver damage if it is ingested. For this reason, thermometers which are only intended to measure typical climatic temperatures now use pigmented alcohol instead; the boiling point of alcohol is higher than any natural temperature expected on Earth. Some medical thermometers still use mercury, for reason of accuracy. Care must be exercised not to bite such a thermometer. The commercial unit for handling mercury is the "flask," which weighs 76 lb.

Mercury is a very dangerous bioaccumulative toxin that is easily absorbed through skin, respiratory and gastrointestinal tissues. Minamata disease is a form of mercury poisoning. Mercury attacks the central nervous system and adversely affects the mouth, gums, and teeth. High exposure over long periods of time will result in brain damage and ultimately death. Air saturated with mercury vapor at room temperature is at a concentration many times the toxic level, despite the high boiling point (the danger is increased at higher temperatures). Mercury should therefore be handled with great care. Containers of mercury need to be covered securely to avoid spillage and evaporation. Heating of mercury or mercury compounds should always be done under a well-ventilated hood; some oxides in particular can decompose into elemental mercury, which immediately evaporates and may not be obvious.

External links

simple:Mercury (element)