Chromium is a lustrous, brittle, hard metal. Its colour is silver-gray and it can be highly polished. It does not tarnish in air, when heated it borns and forms the green chromic oxide. Chromium is unstable in oxygen, it immediately produces a thin oxide layer that is impermeable to oxygen and protects the metal below.
Characteristics:
| Melting point | 1907°C, 3465°F, 2180 K | ||
| Period | 4 | Boiling point | 2671°C, 4840°F, 2944 K |
| Block | d | Density (g cm−3) | 7.15 |
| Atomic number | 24 | Relative atomic mass | 51.996 |
| State at 20°C | Solid | Key isotopes | 52Cr |
| Electron configuration | [Ar] 3d54s1 | CAS number | 7440-47-3 |
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