Tm
Thulium is the rarest naturally occurring lanthanide.
Physical Properties
| Atomic Mass | 168.93 u |
| Density | 9.321 g/cm³ |
| Melting Point | 1818.0 K |
| Boiling Point | 2223.0 K |
| Appearance | Silvery-gray metallic |
| State at Room Temp | Solid |
Chemical Properties
| Electronegativity | 1.25 (Pauling) |
| 1st Ionization Energy | 596.7 kJ/mol |
| Electron Affinity | 99.0 kJ/mol |
| Oxidation States | +2, +3 |
Atomic Properties
| Electron Configuration | [Xe] 4f13 6s2 |
| Atomic Radius | 176.0 pm |
| Covalent Radius | 190.0 pm |
| Van der Waals Radius | 227.0 pm |
Discovery
| Discovered By | Per Teodor Cleve |
| Discovery Year | 1879 |
| Location | Uppsala, Sweden |
| Named After | Thule, a mythical name for Scandinavia |
About Thulium
Thulium is a bright, silvery, lustrous metal and the least abundant naturally occurring lanthanide. Despite its rarity, thulium-170 is used as a portable X-ray source.
Uses & Applications
Portable X-ray devices, high-temperature superconductors, surgical lasers, and anti-counterfeiting.
Fun Fact
Thulium is the least abundant naturally occurring lanthanide, yet it finds use in portable X-ray machines for remote locations.
Isotopes
| Mass Number | Abundance | Half-Life | Stable |
| 169 | 1.0% | - | Yes |
Electron Configuration
[Xe] 4f13 6s2