90 Th 232.04
Thorium
Actinide
Thorium (Th) is a chemical element with atomic number 90, classified as a actinide. At room temperature it is a solid. It was discovered in 1829 by Jöns Jacob Berzelius.
Properties
- Atomic number
- 90
- Atomic mass
- 232.04 u
- Category
- Actinide
- Group
- 0
- Period
- 7
- Block
- f-block
- Electron configuration
- [Rn] 6d² 7s²
- Phase at STP
- Solid
- Density
- 11.72 g/cm³
- Melting point
- 2115 K (1841.8 °C)
- Boiling point
- 5061 K (4787.9 °C)
- Electronegativity
- 1.3
- Atomic radius
- 237 pm
- Ionization energy
- 6.307 eV
- Discovery
- 1829 · Jöns Jacob Berzelius
Common uses
Nuclear reactors, mantles for gas lamps, alloys
Did you know?
Potential nuclear fuel that's more abundant than uranium.
Experiment with the elements
Thorium doesn't form any compounds in our lab yet, but the periodic table sandbox lets you combine dozens of other real elements into real compounds — water, table salt, ammonia and many more — with their true chemical formulas.