Thorium
Thorium, 90Th
 |
| General properties |
| Name, symbol
|
thorium, Th |
| Pronunciation |
THAWR-ee-əm
|
| Appearance |
silvery, often with black tarnish |
|
| Thorium in the periodic table
|
|
|
| Atomic number (Z) |
90 |
|
Group, block
|
group n/a, f-block
|
| Period |
period 7 |
| Element category |
actinide
|
|
Standard atomic weight (±) (Ar)
|
232.0377(4) |
| Electron configuration |
[Rn] 6d2 7s2
|
|
Electrons per shell
|
2, 8, 18, 32, 18, 10, 2 |
| Physical properties |
| Phase |
solid |
| Melting point |
2023 K (1750 °C, 3182 °F) |
| Boiling point |
5061 K (4788 °C, 8650 °F) |
|
Density near r.t.
|
11.7 g/cm3
|
| Heat of fusion |
13.81 kJ/mol
|
| Heat of vaporisation |
514 kJ/mol |
| Molar heat capacity |
26.230 J/(mol·K) |
|
Vapour pressure
|
