Lanthanum

Metal

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

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Electronic 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

Thermal data

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

Steric data

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

Nuclide	Abundance [%]	Mass	Spin	Halflife	Decay mode	Decay 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

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.

Lanthanum

Physical data

Electronic data

Thermal data

Steric data

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