Cerium was the first of the lanthanides to be discovered. It is named after the dwarf planet Ceres, which was discovered two years before the element was isolated. Cerium is highly toxic when pure, but safer cerium compounds have some uses. The main use of cerium is in the manufacture of phosphors. Phosphors are chemical compounds that produce light of different colors, due to the phenomenon of luminescence (either fluorescence or phosphorescence). Luminescent compounds are present in flat screen televisions and light bulbs.

Summary of properties (Ce)

Atomic weight140.116(1)
Discoverer (year)Hisinger, Wilhelm & Berzelius, Jöns Jacob (1803)
Natural formmetallic solid (face centered cubic)
Electron configuration[Xe] 41 5d1 6s2
Melting point (ºC)795
Boiling point (ºC)3257
Abundance in earth's crust (ppm)66.5
Isotope (abundance)136Ce (0.185), 138Ce (0.251), 140Ce (88.450), 142Ce (11.114)
Density g/cm36.77
Van der Waals radius (pm)242
Covalent radius (pm)184
Electronegativity (Pauling)1.12
Vaporization enthalpy (kJ/mol)314.00
Enthalpy of fusion (kJ/mol)5.46
Specific heat capacity (J/g·K) at 25ºC and 1 atm0.19
Thermal conductivity (W/cm·K) at 25ºC and 1 atm0.110
Oxidation state+4, +3
Electron affinity (eV)0.65
1st Ionization potential (eV)5.5387

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