Symbol: Ce
Date of discovery: 1803
Name origin: Ceres
Appearance: gray
Discoverer: W. von Hisinger
Obtained from: monazite, orthite
Melting point: 1068 K
Boiling point: 3633 K
Density[kg/m3]: 6689
Molar volume: 20.69 × 10-6 m3/mol
Protons/Electrons: 58
Neutrons: 82
Shell structure: 2,8,18,19,9,2
Electron configuration: [Xe]4f15d16s2
Oxidation state: 3,4
Crystal structure: hexagonal
Cerium, named after the dwarf planet Ceres, is a soft, malleable, and ductile metal. It is likely to ignite when scratched with a knife, and can ignite spontaneously in air at 65°C to 80°C. Its flames are toxic. Water should not be used to put out cerium fires, as its reaction with water produces hydrogen gas. Although known as a rare earth metal, cerium is not rare at all. Available in large quantities, cerium is even more abundant than lead. This element is widely used in making aluminum and heat-resistant alloys.