Atomic number 20 · alkaline earth · Atomic mass 40.078 u
| Atomic Number | 20 |
| Atomic Mass | 40.0780 u |
| Category | alkaline earth / 碱土金属 |
| Group | 2 |
| Period | 4 |
| Block | S |
| Electron Configuration | [Ar] 4s² |
| Electronegativity (Pauling) | 1 |
| Phase at STP | Solid |
| Density | 1.55 g/cm³ |
| Year Discovered | 1808 |
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