Chromium
Atomic Number: | 24 |
Symbol: | Cr |
Atomic Weight: | 51.996 |
Discovery: | Vauquelin 1797 |
Electron Configuration: | [Ar]4s13d5 |
Word Origin: | Greek chroma: color |
Properties: | Chromium has a melting point of 1857+/-20°C, boiling point of 2672°C, specific gravity of 7.18 to 7.20 (20°C), with valences usually 2, 3, or 6. The metal is a lustous steel-gray color which takes a high polish. It is hard and resistant to corrosion. Chromium has a high melting point, stable crystalline structure, and moderate thermal expansion. All chromium compounds are colored. Chromium compounds are toxic. |
Uses: | Chromium is used to harden steel. It is a component of stainless steel and many other alloys. The metal is commonly used for plating to produce a shiny, hard surface that is resistant to corrosion. Chromium is used as a catalyst. It is added to glass to produce an emerald green color. Chromium compounds are important as pigments, mordants, and oxidizing agents. |
Sources: | The principal ore of chromium is chromite (FeCr2O4). The metal may be produced by reducing its oxide with aluminum. |
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