| Ac | Actinium | Transition Metal |
| Atomic number: | 89 | Atomic weight: | (277.0278) | ||
| Shells: | 2,8,18,32,18,9,2 | Orbitals: | [Rn] 6d1 7s2 | ||
| Melting point: | 1050°C | Boiling point: | 3200°C (±300°C) | ||
| Covalent radius: | -- | Å | Atomic volume: | 22.54 | cm³/mol |
| Atomic radius: | -- | Å | Ionic radius: | -- | Å |
| Electronegativity: | 1.1 | Oxidation states: | |||
| 1st ionization pot.: | 5.17 | V | 2nd ionization pot.: | 12.126 | V |
| 3rd ionization pot.: | -- | V | Specific heat: | -- | J/gK |
| Heat of fusion: | -- | kJ/mol | Heat of vapor.: | -- | kJ/mol |
| Thermal conduct.: | 0.12 | W/cmK | Electrical conduct.: | -- | 10^6/cm ohm |
| Density: | 10.07 | g/cm³ | Valence: | -- |