Thorium (Th)
Thorium (Th, element 90) is an actinide in period 7. Atomic mass 232.038, electron configuration [Rn] 6d² 7s², uses and facts.
About Thorium
Thorium is an actinide with the symbol Th and atomic number 90. It is a solid at room temperature, and it sits in period 7 of the periodic table. Thorium was discovered in 1829 by Jöns Jacob Berzelius.
Thorium key facts
- Atomic number: 90
- Symbol: Th
- Atomic mass: 232.038 u
- Category: actinide
- Group: none (f-block)
- Period: 7
- State at room temperature: solid
- Electron configuration: [Rn] 6d² 7s²
- Electronegativity (Pauling): 1.3
- Melting point: 2115 K (1841.85 °C)
- Boiling point: 5061 K (4787.85 °C)
- Density: 11.72 g/cm³
- Common oxidation states: +1, +2, +3, +4
Electron configuration
The electron configuration of thorium is [Rn] 6d² 7s². The part in brackets is the noble gas core; the rest shows how the outer electrons fill their subshells.
Uses of thorium
- Nuclear fuel (proposed)
- Alloys
- Refractory materials
Did you know?
Thorium is 3× more abundant than uranium and could power civilization for thousands of years as nuclear fuel.
Neighbouring elements
- Actinium (Ac)
- Protactinium (Pa)
- Actinium (Ac)
- Protactinium (Pa)
- Uranium (U)
- Neptunium (Np)
- Plutonium (Pu)
- Americium (Am)
- Curium (Cm)
- Berkelium (Bk)
Frequently asked questions
What is the atomic number of thorium?
The atomic number of thorium is 90, which means every thorium atom has 90 protons.
What is the electron configuration of thorium?
The electron configuration of thorium is [Rn] 6d² 7s².
What group and period is thorium in?
Thorium is an actinide in period 7.
What state is thorium at room temperature?
Thorium is a solid at room temperature.
What is thorium used for?
Thorium is used for nuclear fuel (proposed), alloys, refractory materials.