61 Pm
Lanthanide
Promethium
Radioactive; in luminous paints.
Properties of Promethium
- Atomic number (Z)
- 61
- Symbol
- Pm
- Atomic mass
- 145 g/mol
- Category
- Lanthanide
- Group
- 3
- Period
- 6
- Electron configuration
- [Xe] 4f⁵ 6s²
- Electronegativity (Pauling)
- 1.13
- Atomic radius
- 205 pm
- First ionization energy
- 540 kJ/mol
- Melting point
- 1315 K (1041.8 °C)
- Boiling point
- 3273 K (2999.8 °C)
- Density
- 7.26 g/cm³
- Phase at 25 °C
- Solid
- Discovered
- Discovered in 1945