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Atomic Number: 80
Atomic Symbol: Hg
Atomic Weight: 200.59
Electron Configuration: [Xe]6s24f145d10
History
(Planet Mercury) Known to ancient Chinese and Hindus; found in
Egyptian tombs of 1500 B.C. Mercury is the only common metal liquid at ordinary
temperatures. It only rarely occurs free in nature. The chief ore is cinnabar,
Spain and Italy produce about 50% of the world's supply of the metal. The
commercial unit for handling mercury is the "flask," which weighs 76 lb. The
metal is obtained by heating cinnabar in a current of air and by condensing the
vapor. It is a heavy, silvery-white metal; a rather poor conductor of heat, as
compared with other metals, and a fair conductor of electricity. It easily forms
alloys with many metals, such as gold, silver, and tin, which are called
amalgams. Its ease in amalgamating with gold is made use of in the recovery of
gold from its ores. The most important salts are mercury chloride (corrosive
sublimate - a violent poison), mercurous chloride (calomel, occasionally still
used in medicine), mercury fulminate, a detonator widely used in explosives, and
mercuric sulfide (vermilion, a high-grade paint pigment). Organic mercury
compounds are important. It has been found that an electrical discharge causes
mercury vapor to combine with neon, argon, krypton, and xenon. These products,
held together with van der Waals' forces, correspond to HgNe, HgAr, HgKr, and
HgXe. Mercury is a virulent poison and is readily absorbed through the
respiratory tract, the gastrointestinal tract, or through unbroken skin. It acts
as a cumulative poison and dangerous levels are readily attained in air. Air
saturated with mercury vapor at 20° C contains
a concentration that exceeds the toxic limit many times. The danger increases at
higher temperatures. It is therefore important that mercury be handled with
care. Containers of mercury should be securely covered and spillage should be
avoided. If it is necessary to heat mercury or mercury compounds, it should be
done in a well-ventilated hood. Methyl mercury is a dangerous pollutant and is
now widely found in water and streams. The triple point of mercury, -38.8344°
C, is a fixed point on the International Temperature Scale (ITS-90).
Uses
The metal is widely used in laboratory work for making thermometers,
barometers, diffusion pumps, and many other instruments. It is used in making
mercury-vapor lamps and advertising signs, etc., and is used in mercury switches
and other electronic apparatus. Other uses are in making pesticides, mercury
cells for caustic soda and chlorine production, dental preparations,
anti-fouling paint, batteries, and catalysts.
Sources: CRC Handbook of Chemistry and
Physics and the American Chemical Society.
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