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89
Ac
[227]
Actinium
Actinides · Group 3 · Period 6–7 (f)
Atomic properties
| Atomic number | 89 |
|---|---|
| Symbol | Ac |
| Standard atomic weight | [227] |
| Classification | Actinides |
| Group | f-block series |
| Period | 7 |
| Block | f-block (actinide) |
| Electron configuration | [Rn] 6d1 7s2 |
| Electronegativity (Pauling) | 1.10 |
| Common oxidation states | +3 |
Physical properties
| Phase at 20 °C | Solid |
|---|---|
| Density | 10.07 g/cm³ |
| Melting point | 1050 °C |
| Boiling point | 3200 °C |
| Discovered | 1899 |
| CAS number | — |