61 Pm 145
Promethium
Lanthanide
Promethium (Pm) is a chemical element with atomic number 61, classified as a lanthanide. At room temperature it is a solid. It was discovered in 1945 by Charles D. Coryell et al..
Properties
- Atomic number
- 61
- Atomic mass
- 145 u
- Category
- Lanthanide
- Group
- 0
- Period
- 6
- Block
- f-block
- Electron configuration
- [Xe] 4f⁵ 6s²
- Phase at STP
- Solid
- Density
- 7.26 g/cm³
- Melting point
- 1315 K (1041.8 °C)
- Boiling point
- 3273 K (2999.8 °C)
- Electronegativity
- 1.13
- Atomic radius
- 205 pm
- Ionization energy
- 5.582 eV
- Discovery
- 1945 · Charles D. Coryell et al.
Common uses
Nuclear batteries, luminous paint, research
Did you know?
Only radioactive rare earth element and doesn't occur naturally on Earth.