One of the rarest and most expensive natural elements — extracting 125 g once cost half a million dollars.
- Atomic number
- 91
- Atomic mass
- 231.036 u
- Phase
- Solid
- Electron configuration
- [Rn] 5f² 6d¹ 7s²
- Melting point
- 1,845 K · 1,571.9 °C
- Boiling point
- 4,300 K · 4,026.9 °C
- Density
- 15.37 g/cm³
- Electronegativity
- 1.5
- Period / Group
- 7 / —
- Discovery year
- 1913