| Actinium | |
| Electrons per shell | 2,8,18,32,18,9,2 |
| Electron Configuration | [Rn] 6d1 7s2 |
| Ground state | 2D3/2 |
| Atomic Volume | 22.54 cm3 mol-1 |
| Electronegativity | 1.1 |
| Magnetic ordering | No data |
 Thermal Properties |
|
| Enthalpy of Atomization | 301 kJ mol-1 @25°C |
| Enthalpy of Fusion | 14.2 kJ mol-1 |
| Enthalpy of Vaporisation | 293 kJ mol-1 |
| Heat Capacity | 27.2 J mol-1 K-1 |
| Thermal Conductivity | 12 W m-1 K-1 |
| Thermal Expansion | No data. |
| Electrical Properties |
|
| Electrical resistivity | No data. |
| Electrical conductivity | ? 106/cm Ω |
| Chemical Properties |
|
| Electrochemical Equivalent | 2.82347 g Ah-1 |
| Valence Electron Potential (-eV) | 38.6 |
| Ionization Potential | |
 First
|
5.17 |
| Second
|
12.126 |
| Energy Levels |
|
| Kα1 (intensity 0) |
90.884 KeV |
| Kα2 (intensity 0) |
87.67 KeV |
| Kβ1 (intensity 0) |
102.85 KeV |
| Lα1 (intensity 100) |
12.652 KeV |
| Lα2 (intensity 10) |
12.5008 KeV |
| Lβ1 (intensity 38) |
15.713 KeV |
| Lβ3 (intensity 2) |
15.9261 KeV |
| Lβ4 (intensity 2) |
15.1873 KeV |
| Lγ1 (intensity 8) |
18.408 KeV |
| Lγ2 (intensity 2.7) |
18.728 KeV |
| Lγ3 (intensity 2) |
14.078 KeV |
| Ll (intensity 6) |
10.871 KeV |
| Atomic Radii |
|
| Empirical
|
195 pm |
| Bohr Radius
|
No data. |
| Covalent Radius
|
No data. |
| Van der Waals
|
No data. |
| Triple covalent
|
140 pm |
| Metallic
|
No data. |
| Oxidation States |
|
| Main
|
AcO, Ac+3 |
| Other
|
|
Ionisation Energies (kJ mol-1)  |
|
| M - M+ |
499 |
| M+ - M2+ |
1170 |
| M2+ - M3+ |
1900 |
| M3+ - M4+ |
4700 |
| M4+ - M5+ |
6000 |
| M5+ - M6+ |
7300 |
| M6+ - M7+ |
9200 |
| M7+ - M8+ |
10500 |
| M8+ - M9+ |
11900 |
| M9+ - M10+ |
15800 |
| Crystal Structure |
|
| Structure
|
Cubic close packed |
 |
a = 567 pm |
| b = 567 pm | |
| c = 567 pm | |
| α = 90° | |
| β = 90° | |
| γ = 90° | |