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27
Co
58.933
Cobalt
Transition metals · Group 9 · Period 4
Atomic properties
| Atomic number | 27 |
|---|---|
| Symbol | Co |
| Standard atomic weight | 58.933 |
| Classification | Transition metals |
| Group | 9 |
| Period | 4 |
| Block | d-block |
| Electron configuration | [Ar] 3d7 4s2 |
| Electronegativity (Pauling) | 1.88 |
| Common oxidation states | +3, +2 |
Physical properties
| Phase at 20 °C | Solid |
|---|---|
| Density | 8.90 g/cm³ |
| Melting point | 1495 °C |
| Boiling point | 2927 °C |
| Discovered | 1735 |
| CAS number | — |