NO. 057Lanthanide

La

Lanthanum

Lanthanum is a soft, reactive metal used in camera lenses, catalysts, and hydrogen storage.

Crystal Structure

α form: Double hexagonal close-packed

Atomic Mass138.91 u

Density6.15 g/cm³

Melting Point1193 K

Boiling Point3737 K

Atomic Radius195 pm

Electronegativity1.1

Ionization Energy538 kJ/mol

Electron Affinity48 kJ/mol

Bonding TypeMetallic

Oxidation States3

Acid/BaseBasic

ReactivityHigh

Electron Configuration

[Xe] 5d1 6s2

Discovered ByCarl Gustaf Mosander

Year1839

Known Isotopes

La-139