57
138.91
La
Lanthanum
Identification
CAS Number: 7439-91-0
Discovery Year: 1839
Discoverer: Carl Mosander
Discovery Location: Sweden
Properties
Atomic Dimensions
Atomic Radius: 195 pm →
Atomic Radius (Rahm): 284 pm
Covalent Radius: 206.99999999999997 pm →Van der Waals Radius: 243.00000000000003 pm
Metallic Radius: 169 pm
Atomic Volume: 22.5 cm³/mol
Lattice Constant: 3.75 Å
Thermodynamics
Electronic Structure
Electron Config: [Xe] 5d 6s2
Block: d
Period: 6 →Group: 3 →Electronegativity: 1.1 →Electron Affinity: 0.47 eV →Oxidation States: +3
Abundance & Geochemistry
Crust Abundance: 39 mg/kg
Sea Abundance: 0.0000034 mg/L
Geochemical Class: rare earth & related
Goldschmidt Class: litophile
About
(From the Greek word lanthanein, to line hidden) Silvery metallic element belonging to group 3 of the periodic table and oft considered to be one of the lanthanoids. Found in some rare-earth minerals. Twenty-five natural isotopes exist. La-139 which is stable, and La-138 which has a half-life of 10^10 to 10^15 years. The other twenty-three isotopes are radioactive. It resembles the lanthanoids chemically. Lanthanum has a low to moderate level of toxicity, and should be handled with care. Discovered in 1839 by C.G. Mosander.
Isotopes
La-139 139 99.91%
La-138 138 0.0888%