Atomic number: 55
Category: alkali metal
Density at 25°C: solid: density: 1.93 g·cm−3
Caesium, sometimes spelled cesium, is an alkali metal so it tends to be quite reactive with with water at -116°C. It is quite often used in industry and also in medical imaging. It is mostly found in pollucite ore. Caesium compounds are used as part of drilling fluids.
Use, natural applications or common combinations:
- atomic clocks
- ion thrusters for spacecraft
- Standard atomic weight: 32.905 4519(2)
- Melting point: 28.44 °C
- Boiling point: 671 °C
- Radioactivity: mostly naturally stable
- some isotopes (137Cs) are used industrially with a half-life of around 30 years emitting gamma rays. It is used for radiotherapy. Also used for sterilisation disinfection.