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Lanthanum

Metalsolid
Symbol: La
Atomic number: 57
Atomic mass: 138.9055
Group: Lanthanide
CAS-number: 7439-91-0

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Physical data
Isotopes
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Physical data

Electronic dataThermal dataSteric data
Shells: 2, 8, 18, 18, 9, 2
Orbitals: [Xe] 5d1 6s2
Electronegativity: 1.0, 1.1
1. Ionization potential: 5.5770 eV
2. Ionization potential: 11.059 eV
3. Ionization potential: 19.174 eV
Oxidation states: 3
Electrical conductivity: 0.0126 10^6
Melting point: 918 °C
Boiling point: 3464 °C
Specific heat: 0.19 J/gK
Heat of fusion: 6.20 kJ/mol
Heat of vaporization: 414.0 kJ/mol
Thermal conductivity: 0.135 W/cmK
Atomic radius: 2.74 Å
Ionic radius: 1.16 Å (+3)
Covalent radius: 1.69 Å
Atomic volume: 20.73 cm³/mol
Density (293 K): 6.7 g/cm³
Crystal structure: hexagonal
hexagonal

Isotopes

NuclideAbundance [%]MassSpinHalflifeDecay modeDecay tree
137La 0 137 7/2 6E04y EC View
138La 0.089 137.907 5 1.05E11y EC, β- View
139La 99.911 138.906 7/2 -- --
140La 0 140 3 1.678d β- View
141La 0 141 7/2 3.90h β- View
142La 0 142 2 1.54m β- View

Other info

Name origin:Greek: lanthanein (to be hidden).
Description:Soft, silvery-white, malleable, ductile metal.
Discovered by:Carl Mosander
Year:1839
Place:Sweden
Sources:Found with rare earths in monazite and bastnasite. Monazite sand typically contains 25% lanthanum.
Use(s):It is used in the electrodes of high-intensity, carbon-arc lights. Also used in the production of high-grade europium metal. Because it gives glass refractive properties, it is used in expensive camera lenses.