Lanthanum (La)
Lanthanum (La) is element 57, a lanthanide. Atomic mass 138.90547, configuration [Xe] 5d¹ 6s². Properties, isotopes, oxidation states, uses and history, with an interactive 3D atom model.
Key facts
| Atomic number | 57 |
|---|---|
| Symbol | La |
| Standard atomic weight | 138.90547(7) |
| Category | Lanthanide |
| Period | 6 |
| State at room temperature | Solid |
| Electron configuration | [Xe] 5d¹ 6s² |
| Valence electrons | 2 (Variable) |
| Common oxidation states | +3 |
| Common ions | No common ions |
| Electronegativity (Pauling) | 1.1 |
| First ionization energy | 538 kJ/mol |
| Electron affinity | 45.35 kJ/mol |
| Atomic radius | 195 pm |
| Density | 6.15 g/cm³ |
| Melting point | 919°C |
| Boiling point | 3464°C |
| Specific heat | 0.195 J/(g·°C) |
Natural isotopes
- La-138: Radioactive
- La-139: Stable
Common uses
- Camera lenses (High refractive index glass)
- Hybrid car batteries
- Lighter flints
Where it matters
- Hybrid Vehicles (NiMH batteries)
Hazards
- Low toxicity
- dust is flammable
History
| Discovered | 1839 |
|---|---|
| Discovered by | Carl Gustaf Mosander |
| Name | From Greek lanthanein (to lie hidden) |