Mercury’s symbol is Hg, its atomic number is 80, its atomic mass is 200.59, its in group 12 and in period 6, and it also has two valence electrons. Its standard state is liquid at 298ºK and it is the heaviest known elemental liquid. It has a silvery white color. It is named after the planet Mercury the origin of the symbol Hg is the Latin word hydrargyrum meaning liquid silver.
Mercury was known to ancient Chinese and Hindus before 2000 B.C. and was found in tubes in Egyptian tombs dated from 1500 B.C. Mercury is the only metal liquid at ordinary temperatures. Mercury is sometimes called quicksilver. It sometimes occurs free in nature and is found mainly in cinnabar ore, which is HgS. Cinnabar ore is found in Spain and Italy.
Mercury is a heavy, silvery-white metal, which forms alloys easily with many metals like gold, silver, and tin. These alloys are called amalgams. Its way of amalgamating with gold is made use of the recovery of gold from its ores. Mercury is a bad conductor of heat and an okay conductor of electricity. The most important salts are mercuric chloride HgC12 that is a corrosive and violent poison. Mercurous chloride Hg2Cl2, which used to be used in medicine. Mercury fulminate Hg(ONC)2 used as a detonator in explosives and mercuric sulfide HgS used as a high-grade paint pigment.
Organic mercury compounds are important and dangerous. Methyl mercury is a lethal pollutant found in rivers and lakes. 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 since there are few pathways available to the body for its excretion. Since mercury is a very readily vaporizable element at a relatively low temperature, 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. Mercury should only be handled under a well-ventilated area. Mercury is well known because of its use in many thermometers. It was common to demonstrate the formation of mercury in the laboratory by heating mercury sulfide. This method forms the basis of commercial extraction to get mercury. The prepared cinnabar ore is heated in a current of air and the mercury vapor condensed.
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http://encarta.msn.com © 1997-2000 Microsoft Corporation. All rights reserved.
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Volume M-R. Pages 253-260.