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| Atomic Number: | 24 | Atomic Symbol: | Cr | | Atomic Weight: | 51.996 | Electron Configuration: | 2-8-13-1 | | Shells: | 2,8,13,1 | Filling Orbital: | 3d5 | | Melting Point: | 1857oC | Boiling Point: | 2672oC | | Uses: | make stainless steels, plating metal sheets (cars) gives color to
ruby's and emeralds |
History(Gr. chroma, color) Discovered in 1797 by Louis Vauquelin of
France, who prepared the metal the next year, chromium is a steel-gray,
lustrous, hard metal that takes a high polish.
SourcesThe principal ore is chromite, which is found in Zimbabwe,
Russia, Transvaal, Turkey, Iran, Albania, FInland, Democratic Republic of
Madagascar, and the Phillippines.
The metal is usually produced by reducing
the oxide with aluminum.
UsesChromium is used to harden steel, to manufacture stainless steel,
and to form many useful alloys.
Much is used in plating to produce a hard,
beautiful surface and to prevent corrosion.
Chromium gives glass an emerald
green color and is widely used as a catalyst.
The refractory industry has
found chromite useful for forming bricks and shapes, as it has a high melting
point, moderate thermal expansion, and stability of crystalline structure.
CompoundsAll compounds of chromium are colored; the most important are
the chromates of sodium andpotassium
and the dichromates and the potassium and ammonium chrome
alums. The dichromates are used as oxidizing agents in quantitative analysis,
also in tanning leather.
Other compounds are of industrial value; lead chromate is chrome yellow, a
valued pigment. Chromium compounds are used in the textile industry as mordants,
and by the aircraft and other industries for anodizing aluminum.
HandlingChromium compounds are toxic and should be handled with proper
safeguards
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