Tm
Thulium (Atomic Number 69)
Category: lanthanide | Period 6, Group 3 | Block: f
Second rarest lanthanide; emits targeted X-rays when irradiated.
Atomic & Physical Constants
- Standard Atomic Weight:
- 168.934222 u
- Standard State Phase:
- Solid
- Electron Configuration:
- 2, 8, 18, 31, 8, 2
- Electronegativity (Pauling):
- 1.25
- Melting Point:
- 1818 K
- Boiling Point:
- 2223 K
Historical Discovery & Real-World Applications
Industrial & Scientific Uses
Portable medical X-ray sources, surgical solid-state lasers
Discovery History
Discovered by Per Teodor Cleve (1879).
Study Thulium with Socratic AI Tutor
Get step-by-step orbital hybridization, oxidation state derivations, and reaction practice questions.