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Facts About Chromium

Chromium
Credit: Greg Robson/Creative Commons, Andrei Marincas | Shutterstock
Atomic Number: 24
Atomic Symbol: Cr
Atomic Weight: 51.9961
Melting Point: 3,465 F (1,907 C)
Boiling Point: 4,840 F (2,671 C)

Word origin: The word chromium comes from the Greek word chroma (color).

Discovery: Chromium was discovered in 1797 by Louis Nicolas Vauquelin.

Properties of chromium

Chromium is a transition metal in Group 6 on the Periodic Table of Elements. In its pure form, chromium is a steel-gray, lustrous hard metal that has a high polish. It has many compounds that are all colored. [See Periodic Table of the Elements]

Of the compounds, the most important are the chromates of sodium and potassium; the dichromates; and potassium and ammonium chrome alums. Chromium compounds are toxic and should be handled with care.

Chromite ore
Chromite ore is the main source of pure chromium.
Credit: inanavci | Shutterstock

Sources of chromium

Chromium is principally found in chromite ore. Chromite is found in Zimbabwe, Russia, New Zealand, Turkey, Iran, Albania, Finland, the Philippines and Madagascar.

The metal is used usually produced by reducing the oxide with aluminum.

Uses of chromium

Chromium is used to harden steel, to manufacture stainless steel, and as part of many useful alloys. Plating is its most common use; it produces a hard, shiny, beautiful surface and prevents corrosion. Chromium gives glass an emerald green color and is widely used as a catalyst.

The refractory industry uses chromite in forming bricks and shapes. It is useful for this because it has a high melting point, moderate thermal expansion, and crystalline structure stability.

Chromium’s compounds are also very useful. Dichromates are used as oxidizing agents in quantitive analysis and in tanning leather. Lead chromate is chrome-yellow, a valued pigment.Chromium compounds are used in the textile industry as mordants. They are also used for anodizing aluminum in the aircraft and other industries.

(Source: Los Alamos National Laboratory)

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