Cesium
Symbol: Cs

Atomic Number: 55
Atomic Weight: 132.905
Protons: 55
Neutrons: 78
Electrons: 55
Group: Alkali Metals (IA)

Brief Description:
Cesium is a soft, silver-white metal. It is one of the few metals that can be liquid at or around room temperature, but is usually found as a solid. It reacts violently with cold water, often with explosive effects. Spelled "caesium" in the UK and other nations.