Lanthanum

Symbol: La
Atomic number: 57
Category: lanthanides
Group: 3
Period: 6
Block: f
Atomic weight: 138.90547 g/mol
Electrons per shell: 2, 8, 18, 18, 9, 2
CAS number: 7439-91-0
Phase: solid
Density: 6.162 kg/l (near room temperature)
Melting point: 1193 K (920C, 1688F)
Boiling point: 3737 K (3464C, 6267F)
Crystal structure: hexagonal
Oxidation states: 3
Electronegativity: 1.10 (Pauling scale)
Name's origin: lanthano
Name's meaning: a Greek word which means 'to lie hidden'
Facts:
- is found in some rare-earth minerals, usually in combination with cerium and other rare earth elements
- is malleable, ductile, and soft enough to be cut with a knife
- is one of the most reactive of the rare-earth metals
- reacts directly with elemental carbon, nitrogen, boron, selenium, silicon, phosphorus, sulfur, and with halogens
- oxidizes rapidly when exposed to air
- has no known biological role
- uses include carbon lighting applications, metal additive, petroleum cracking catalysts, glass polishing compound etc.