Cesium
Cesium (Cs), atomic number 55, is a highly reactive alkali metal. It is soft and silvery-golden, with a melting point of 28.5°C and a density of 1.93 g/cm3. It reacts vigorously with water and air, forming oxides, hydroxides, and peroxides.
In nature, cesium is rare in the Earth's crust, occurring only in trace amounts and primarily in
The most important isotopes are Cs-133, which is stable, and Cs-137, a radioactive product of nuclear fission.
Applications span scientific, medical, and industrial fields. Cs-137 is used in radiotherapy and industrial gauges, while
Handling cesium requires care because of its reactivity with moisture and air; it is typically stored under