89 Ac
Actinide
Actinium
First actinide.
Properties of Actinium
- Atomic number (Z)
- 89
- Symbol
- Ac
- Atomic mass
- 227 g/mol
- Category
- Actinide
- Group
- 3
- Period
- 7
- Electron configuration
- [Rn] 6d¹ 7s²
- Electronegativity (Pauling)
- 1.1
- Atomic radius
- 195 pm
- First ionization energy
- 499 kJ/mol
- Melting point
- 1323 K (1049.8 °C)
- Boiling point
- 3471 K (3197.8 °C)
- Density
- 10.07 g/cm³
- Phase at 25 °C
- Solid
- Discovered
- Discovered in 1899