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Chromium


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Atomic Number:24Atomic Symbol:Cr
Atomic Weight:51.996Electron Configuration:2-8-13-1
Shells:2,8,13,1Filling Orbital:3d5
Melting Point:1857oCBoiling 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.

Sources

The 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.

Uses

Chromium 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.

Compounds

All 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.

Handling

Chromium compounds are toxic and should be handled with proper safeguards

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