Element 57
Lanthanum (La)
Lanthanum (La) is element 57 of the periodic table, a lanthanide in period 6 (f-block) with an atomic mass of 138.91 and is a solid at standard conditions.
At a glance
- Atomic number
- 57
- Symbol
- La
- Atomic mass
- 138.91 u
- Category
- Lanthanides
- Period
- 6
- Block
- f-block
- Phase at STP
- solid
Electron structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 5d1 6s2
- Shorthand configuration
- [Xe] 5d1 6s2
- Electrons per shell
- 2, 8, 18, 18, 9, 2
- Oxidation states
- +1, +2, +3
Physical properties
- Melting point
- 1193 K
- Boiling point
- 3737 K
- Density
- 6.145 g/cm3
- Phase
- solid
Atomic properties
- Electronegativity (Pauling)
- 1.1
- Atomic radius
- 195 pm
- Covalent radius
- 207 pm
- First ionization energy
- 538 kJ/mol
- Electron affinity
- 50 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| La-139 | 138.90635 | 99.91% | Stable |
Common uses
- Hybrid car batteries
- Camera lenses
- Lighting
- Catalysts
Discovery
- Year
- 1839
- Discovered by
- Carl Gustaf Mosander
- Country
- Sweden