Lanthanum
lanthanideProperties
| Property | Value |
|---|---|
| Atomic Mass | 138.91 amu |
| Category | lanthanide |
| Period | 6 |
| Electron Configuration | [Xe] 5d1 6s2 |
| Electronegativity | 1.1 (Pauling) |
| Oxidation States | 3 |
| Melting Point | 1193 K (919.9 °C) |
| Boiling Point | 3737 K (3463.8 °C) |
| Density | 6.162 g/cm³ |
| Discovered By | Carl Gustaf Mosander (1839) |
About Lanthanum
Lanthanum is the element that gives the lanthanide series its name, and the name itself is a confession — from the Greek lanthanein, meaning to lie hidden. Mosander spent years pulling it out of cerium oxide before he could prove it was a separate element in 1839. The metal is soft enough to cut with a knife, tarnishes within minutes once you expose a fresh surface to air, and reacts with cold water on contact. Despite the rare-earth label, La is more abundant in the crust than lead, but it never shows up uncombined — you always extract it from monazite or bastnäsite alongside the rest of its stubborn family. Chemically La sticks almost exclusively to the +3 state, and that single oxidation number is part of why separating the lanthanides from each other took chemists more than a century. Modern uses lean on what La does well: hydrogen-absorbing alloys for NiMH batteries, high-index optical glass that drops chromatic aberration in camera lenses, and cracking catalysts in petroleum refineries.
Fun Fact
Lanthanum literally means 'hidden one' — it evaded detection for 36 years while hiding inside cerium minerals, a fitting name for an element that launched an entire series of notoriously hard-to-separate elements.
Common Uses
- Hydrogen-absorbing anode in nickel-metal hydride batteries
- High-refractive-index glass for camera and telescope lenses
- Fluid catalytic cracking catalysts in petroleum refining
- Mischmetal lighter flints (50% La with Ce, Nd, Pr)
- Hydrogen storage alloys for fuel cell research