Th
Thorium
Thorium is a chemical element with the symbol Th and atomic number 90. It has a standard atomic weight of 232.04, sits in period 7 of the f-block, and is classified as an actinide.
Properties
| Symbol | Th |
|---|---|
| Atomic number | 90 |
| Standard atomic weight | 232.04 |
| Category | Actinide |
| Group | f-block — no group |
| Period | 7 |
| Electron configuration | [Rn] 5f2 7s2 |
| Outer-shell electrons | 2 |
The figure of 232.04 is a standard atomic weight.
Calculate with thorium
- Molar mass of any formula containing it
- Electron configuration, including ions
- Effective nuclear charge by Slater's rules
- Average atomic mass from isotope abundances
Atomic weights are the IUPAC 2021 standard values, abridged to the conventional five significant figures. Group, period, category and electron configuration are derived from the atomic number rather than stored, so they cannot drift out of step with it.