A silver-gray, lustrous, brittle, hard metallic → chemical element that is resistant to tarnish and corrosion; symbol Cr. → Atomic number 24; → atomic weight 51.996; → melting point about 1,857°C; → boiling point about 2,672°C; → specific gravity about 7.2 at 20°C. Chromium is used in the hardening of steel alloys and the production of stainless steels. It is extracted by reducing the oxide with → aluminium. Its → radioactive isotope 51Cr has a half-life of 27.8 days. It was discovered in 1797 by the French chemist and pharmacist Nicolas-Louis Vauquelin (1763-1829).
From the Gk. chroma "color," from the many colored compounds of this element, + -ium a suffix used in the name of several chemical elements.