Lanthanum (La)

Soft, silvery-white metal

Lanthanum is the namesake of the lanthanide series, used in camera lenses, catalysts, and hybrid car batteries, and with [Xe] 5d¹ 6s², lanthanum has a large ionic radius (103 pm for La³⁺) making it useful in cracking catalysts. Nickel-metal hydride batteries use lanthanum-based alloys as the hydrogen-absorbing electrode.

Key metrics

Density6.15g/cm³

Melting point1,193K

Boiling point3,737K

Electronegativity1.1Pauling

Discovery

1839discovered

Discovered by: Carl Gustaf Mosander
Reactivity profile: Oxidizes rapidly
Reactivity: High
Bonding: Metallic

Electron configuration

\textcolor{#6b7280}{[Xe]}\; \textcolor{#22c55e}{5_{d}^{1}}\; \textcolor{#ef4444}{6_{s}^{2}}

[Xe] 5d1 6s2

Wave function

\Psi_{\text{La}} \approx \frac{1}{\sqrt{57!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{57}(\mathbf{r}_{57}) \right|

Probability density $|\Psi|^2$ across the La valence shell.

Crystal structure

Double Hexagonal Close-Packed

Lattice constantsa 1.00 · b 1.00 · c 2.00

Cell anglesα 90° · β 90° · γ 120°

Coordination number12

Atoms per cell4

Atomic packing factor0.74

Physical properties

Atomic radius: 195 pm
Ionization energy: 538 kJ/mol
Electron affinity: 48 kJ/mol
Crystal structure: α form: Double hexagonal close-packed

Oxidation states

Acid/base

Basic

Strongly acidicStrongly basic

State at 25 °CSolid

1193 K3737 K298 K

Emission spectrum

3 transitions

380450500550600650700780

VioletBlueGreenYellowRed

442.6nmLa I (blue)Violet100%

531.2nmLa I (green)Green60%

625.0nmLa I (orange)Orange40%

Dominant line 442.6 nmRange 443–625 nmTransitions 3