A soft alkali metal whose spectral line is deep red, and whose ions run some of the world's most precise clocks.
- Atomic number
- 37
- Atomic mass
- 85.468 u
- Phase
- Solid
- Electron configuration
- [Kr] 5s¹
- Melting point
- 312.46 K · 39.3 °C
- Boiling point
- 961 K · 687.9 °C
- Density
- 1.532 g/cm³
- Electronegativity
- 0.82
- Period / Group
- 5 / 1
- Discovery year
- 1861