Chromium. Number 24. Cr. Atomic weight: 51.9961.
Electron Configuration
Melting Point
Boiling point
Density
Color
Common Ion Charges
Reactions
Common Compounds
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[Ar] 4s2 3d4
1907°C
2671°C
7140kg m^-3
Silver metallic
Cr2+ and Cr3+
Does not react with water, reacts with oxygen to form chromium (III) oxide, reacts with most acids (such as hydrocloric acid), also reacts with fluorine at high temps
Chromium diflouride, Chromium triflouride, Chromium dichloride, Chromium trichloride, Chromium dibromide, Chromium tribromide, Chromium diiodide, Chromium dioxide, Chromium sulphide, Chromium nitride
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Discovery: Chromium was discovered by Louis-Nicholas Vauquelin in 1797 in France. The name comes from the Greek word "Chroma" which means "colour", because chromium has many colorful compounds. After Vauquelin, German chemist Tassert found chromium in an ore called chromite (Fe(CrO2)2), which today is a source of chromium.
Uses: Chromium plating on cars and bicycles produces a beautiful silver finish that is resistant to corrosion. It also hardens steel to make stainless steel and to make alloys. It is widely used as a catalyst, and for its colorful pigments. Chromium (III) sulfate is used for tanning leather. Chromium is also found in emeralds and rubies, and is also found in human bodies.
Hazards: Chromium is not harmful and is a trace element in humans, but hexavalent chromium (Cr(VI)) is extremely toxic and carcinogenic.
Uses: Chromium plating on cars and bicycles produces a beautiful silver finish that is resistant to corrosion. It also hardens steel to make stainless steel and to make alloys. It is widely used as a catalyst, and for its colorful pigments. Chromium (III) sulfate is used for tanning leather. Chromium is also found in emeralds and rubies, and is also found in human bodies.
Hazards: Chromium is not harmful and is a trace element in humans, but hexavalent chromium (Cr(VI)) is extremely toxic and carcinogenic.