89 Ac Actinium [227]
Actinide
Actinium 锕
[Rn] 6d¹ 7s²
- Period 7
- Group —
- Block f
- Solid
Electron configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁶ 6d¹ 7s²
Orbital diagram (valence)
- Electrons per shell
- 2, 8, 18, 32, 18, 9, 2
- Unpaired electrons
- 1
- Zeff (Slater)
- 3.00
Properties
- Atomic weight
- [227]
- Electronegativity (Pauling)
- 1.1
- First ionization energy
- 498.8 kJ/mol
- Electron affinity
- no data
- Covalent radius
- 215 pm
- van der Waals radius
- 260 pm
- Melting point
- 1324 K
- Boiling point
- 3471 K
- Density
- 10.07 g/cm³
- Melting / boiling point
- 1050.8 °C / 3197.8 °C
- Common oxidation states
- +3
- Discovered
- 1899
Brackets give the mass number of the longest-lived isotope
Periodic trend
Data: PubChem periodic table (public domain); atomic weights are IUPAC abridged standard values; covalent radii from Cordero et al. (2008).