57 La
Lanthanide
Lanthanum
Used in camera lenses.
Properties of Lanthanum
- Atomic number (Z)
- 57
- Symbol
- La
- Atomic mass
- 138.91 g/mol
- Category
- Lanthanide
- Group
- 3
- Period
- 6
- Electron configuration
- [Xe] 5d¹ 6s²
- Electronegativity (Pauling)
- 1.1
- Atomic radius
- 226 pm
- First ionization energy
- 538 kJ/mol
- Melting point
- 1193 K (919.9 °C)
- Boiling point
- 3737 K (3463.8 °C)
- Density
- 6.145 g/cm³
- Phase at 25 °C
- Solid
- Discovered
- Discovered in 1839