69 Tm
Lanthanide
Thulium
Rarest natural lanthanide.
Properties of Thulium
- Atomic number (Z)
- 69
- Symbol
- Tm
- Atomic mass
- 168.93 g/mol
- Category
- Lanthanide
- Group
- 3
- Period
- 6
- Electron configuration
- [Xe] 4f¹³ 6s²
- Electronegativity (Pauling)
- 1.25
- Atomic radius
- 222 pm
- First ionization energy
- 597 kJ/mol
- Melting point
- 1818 K (1544.8 °C)
- Boiling point
- 2223 K (1949.8 °C)
- Density
- 9.321 g/cm³
- Phase at 25 °C
- Solid
- Discovered
- Discovered in 1879