Basic Information

Name: Cesium 
Symbol: Cs 
Atomic Number: 55 
Atomic Mass: 132.90546 amu 
Melting Point: 28.5 °C (301.65 K, 83.3 °F) 
Boiling Point: 678.4 °C (951.55005 K, 1253.12 °F) 
Number of Protons/Electrons: 55 
Number of Neutrons: 78 
Classification: Alkali Metal 
Crystal Structure: Cubic 
Density @ 293 K: 1.873 g/cm3 
Color: silver 
British Spelling: Caesium 
IUPAC Spelling: Caesium
Date of Discovery: 1860 
Discoverer: Fustov Kirchoff 
Name Origin: From the Latin word caesius (sky blue) 
Uses: removes air traces in vacuum tubes 
Obtained From: pollucite, lepidolite