Thulium
Thulium (铥, symbol Tm) is chemical element number 69, a Lanthanide in period 6 of the periodic table, with a standard atomic weight of about 168.93. Rarest naturally occurring lanthanide. Used in portable X-ray devices.
Properties
| Atomic number | 69 |
|---|---|
| Symbol | Tm |
| Atomic mass | 168.93 u |
| Category | Lanthanide |
| Period | 6 |
| Group | — |
| Electron configuration | [Xe] 4f¹³ 6s² |
| Electronegativity | 1.25 |
| Covalent radius | 190 pm |
| Density | 9.321 g/cm³ |
| Melting point | 1818 K |
| Boiling point | 2223 K |
| Discovery | Per Teodor Cleve, 1879 |
Overview
Rarest naturally occurring lanthanide. Used in portable X-ray devices. Element 69, Thulium (Tm), is a Lanthanide found in period 6. As a lanthanide (rare-earth) element it closely resembles its neighbours and serves in magnets, phosphors and catalysts.
It has the configuration [Xe] 4f¹³ 6s² and an electronegativity near 1.25; its 2 outer-shell electrons drive its bonding. Under standard conditions it exists as a solid; it melts near 1818 K (1544.9 °C), boils near 2223 K (1949.9 °C), has a density around 9.321 g/cm³.
It is widely used in Medical / Pharma and Research. It was first described by Per Teodor Cleve in 1879. The periodic trends guide explains the underlying patterns.
Electron shells
Electrons per shell: 2 · 8 · 18 · 31 · 8 · 2
Main uses
- Medical / Pharma
- Research
Hazard
Compounds containing Thulium
No compounds in this knowledge base contain Thulium yet.
Data sources
Atomic mass uses IUPAC (CIAAW) standard atomic weights; the covalent radius is from Cordero et al. (2008). Verify on the RSC Periodic Table, PubChem and Wikipedia. Educational reference only.