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20
Ca
40.078
Calcium
Alkaline earth metals · Group 2 · Period 4
Atomic properties
| Atomic number | 20 |
|---|---|
| Symbol | Ca |
| Standard atomic weight | 40.078 |
| Classification | Alkaline earth metals |
| Group | 2 |
| Period | 4 |
| Block | s-block |
| Electron configuration | [Ar] 4s2 |
| Electronegativity (Pauling) | 1.00 |
| Common oxidation states | +2 |
Physical properties
| Phase at 20 °C | Solid |
|---|---|
| Density | 1.55 g/cm³ |
| Melting point | 842 °C |
| Boiling point | 1484 °C |
| Discovered | 1808 |
| CAS number | — |