Lanthanum (La) is chemical element 57, a lanthanide in the f-block, period 6 (PubChem).
- Atomic number: 57
- Symbol: La
- Group: none (f-block)
- Period: 6
- Atomic mass: 138.9055 u
- Electron configuration: [Xe]6s2 5d1
- Electronegativity (Pauling scale): 1.1
- Atomic radius (van der Waals): 240 pm
- Ionization energy: 5.577 eV
- Electron affinity: 0.5 eV
- Oxidation states: +3
- Standard state: Solid
- Melting point: 1191 K
- Boiling point: 3737 K
- Density: 6.15 g/cm³
- Chemical group: Lanthanide
- Year discovered: 1839