Thorium (Th)
Thorium (Th) is element 90, an actinide. Atomic mass 232.0377, configuration [Rn] 6d² 7s². Properties, isotopes, oxidation states, uses and history, with an interactive 3D atom model.
Key facts
| Atomic number | 90 |
|---|---|
| Symbol | Th |
| Standard atomic weight | 232.0377(4) |
| Category | Actinide |
| Period | 7 |
| State at room temperature | Solid |
| Electron configuration | [Rn] 6d² 7s² |
| Valence electrons | 2 (Variable) |
| Common oxidation states | +4 |
| Common ions | No common ions |
| Electronegativity (Pauling) | 1.3 |
| First ionization energy | 587 kJ/mol |
| Atomic radius | 180 pm |
| Density | 11.7 g/cm³ |
| Melting point | 1747°C |
| Boiling point | 4788°C |
| Specific heat | 0.118 J/(g·°C) |
Common uses
- Gas lantern mantles
- TIG welding electrodes
- Nuclear fuel potential
Where it matters
- Future Energy (Thorium molten salt reactors)
Hazards
- Low radioactivity
- heavy metal toxicity
History
| Discovered | 1829 |
|---|---|
| Discovered by | Jöns Jakob Berzelius |
| Name | Thor (Norse god of thunder) |