Atomic number: 61
Category: lanthanoid metal
Density at 25°C: solid: density: 7.26 g·cm−3 [7.220]
All forms of promethium are radioactive. This partly explains why it was hard to discover initially and in fact wasn't produced until about 1945 in a laboratory in the US.
Use, natural applications or common combinations:
- specialised batteries
- some long lasting glowing paints
- used for measuring thicknesses of materials
- Standard atomic weight: [144.913] varies
- Melting point: 1042 °C
- Boiling point: 3000 °C
- Radioactivity: all radioactive.
- 145Pm half life of 17.7 years decays via electron capture ( usually releases a gamma ray)
- 147Pm half life 2.63 years beta- decay (electrons released) meaning less hazardous. some x-rays released.