cobalt (Co)

Cobalt. Credit: RTC, Wikipedia

A hard, brittle, silvery-gray metallic element in group VIII of the periodic table; it is ferromagnetic (see ferromagnetism) and a transition element. Cobalt is found associated with nickel, silver, lead, copper, and iron ores (notably cobaltite and smaltite), and resembles nickel and iron both chemically and in appearance. It was discovered by Georg Brandt in Stockholm, Sweden, in 1735; its name is derived from the German kobald, meaning "goblin" (from the belief of silver miners it had been placed by goblins who had stolen the silver).

An alloy of cobalt, called Alnico, which also contains aluminum, nickel, and iron, is used for making magnets; other cobalt alloys, being very hard, are used for cutting tools. Cobalt is used as the matrix for tungsten carbide in drill bits. Its colored salts are used in blue glass and the artists' pigment cobalt blue. Cobalt catalysts facilitate hydrogenation and other industrial processes. The radioisotope cobalt-60 is used as a source of gamma rays, in radiation therapy and tracer studies, and has also been used in some countries to irradiate food to preserve it..

Cobalt is an essential element for humans since it is part of vitamin B₁₂. The amount needed is very small, and an avergae person's body contains only about 1 milligram of the element.

Cobalt's characteristic oxidation states are +2 and +3.

atomic number	27
relative atomic mass	58.933
electronic configuration	1s²2s²2p⁶3s²3p⁶4s²3d⁷
main oxidation states	+2, +3
relative density	8.9
melting point	1,495°C (2,723°F)
boiling point	3,100°C (5,612°F)

Related category

• INORGANIC CHEMISTRY

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