Lanthanum (La)

Lanthanum is a soft, ductile, silvery-white metallic chemical element, the namesake of the lanthanide series.

Core Principles & Analysis

• Carl Gustaf Mosander discovered lanthanum in 1839 hidden within cerium nitrate, naming it from the Greek for 'to lie hidden'.
• It is the soft, silvery first member of the lanthanide series and can be cut with a knife.
• Lanthanum raises the refractive index of premium camera lens glass and forms the hydrogen-storing alloy in nickel-metal hydride batteries.

Specifications & Metrics

• NUM: 57
• SYMBOL: La
• CATEGORY: Lanthanide
• ATOMIC MASS: 138.9055 u
• ELECTRONEGATIVITY: 1.1 Pauling
• ATOMIC RADIUS: 240 pm
• IONIZATION ENERGY: 5.577 eV
• ELECTRON AFFINITY: 0.5 eV
• MELTING POINT: 1191 K
• BOILING POINT: 3737 K
• DENSITY: 6.15 g/cm³
• ELECTRON CONFIGURATION: [Xe]6s2 5d1
• OXIDATION STATES: +3
• STANDARD STATE: Solid
• GROUP BLOCK: Lanthanide
• YEAR DISCOVERED: 1839