Although the word "lanthanum" means "being hidden", it is more abundant than most metals. For example, it is three times more common than lead. This element was discovered in the mineral cerite in 1839. However, it took chemists almost another 100 years to find a way to purify it. Today, the main source of pure lanthanum is the mineral bastnasite. Lanthanum's applications range from its use in film studio lights and lens manufacturing to petroleum refining.

Summary of properties (Lai)

Atomic weight138.90547(7)
Discoverer (year)Mosander, Carl Gustav (1839)
Natural formmetallic solid (hexagonal)
Electron configuration[Xe] 5d1 6s2
Melting point (ºC)920
Boiling point (ºC)3469
Abundance in earth's crust (ppm)39
Isotope (abundance)138La (0.090), 139La (99.910)
Density g/cm36.15
Van der Waals radius (pm)243
Covalent radius (pm)194
Electronegativity (Pauling)1.1
Vaporization enthalpy (kJ/mol)399.60
Enthalpy of fusion (kJ/mol)6.20
Specific heat capacity (J/g·K) at 25ºC and 1 atm0.20
Thermal conductivity (W/cm·K) at 25ºC and 1 atm0.130
Oxidation state+3
Electron affinity (eV)0.47
1st Ionization potential (eV)5.5769

Back to the Periodic Table of the Elements.