Tm
Thulium
Thulium is a chemical element with the symbol Tm and atomic number 69. It has a standard atomic weight of 168.93, sits in period 6 of the f-block, and is classified as a lanthanide.
Properties
| Symbol | Tm |
|---|---|
| Atomic number | 69 |
| Standard atomic weight | 168.93 |
| Category | Lanthanide |
| Group | f-block — no group |
| Period | 6 |
| Electron configuration | [Xe] 4f13 6s2 |
| Outer-shell electrons | 2 |
The figure of 168.93 is a standard atomic weight.
Calculate with thulium
- 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.