Template:Infobox lanthanum

Lanthanum,  ₅₇La

General properties
Name, symbol	lanthanum, La
Appearance	silvery white
Pronunciation	/ˈlænθənəm/
Lanthanum in the periodic table
– ↑ La ↓ Ac barium ← lanthanum → cerium
Atomic number (Z)	57
Group, block	group n/a, f-block
Period	period 6
Element category	lanthanide, sometimes considered a transition metal
Standard atomic weight (±) (Ar)	138.90547(7)
Electron configuration	[Xe] 5d1 6s2
per shell	2, 8, 18, 18, 9, 2
Physical properties
Phase	solid
Melting point	1193 K ​(920 °C, ​1688 °F)
Boiling point	3737 K ​(3464 °C, ​6267 °F)
Density near r.t.	6.162 g/cm3
when liquid, at m.p.	5.94 g/cm3
Heat of fusion	6.20 kJ/mol
Heat of vaporization	400 kJ/mol
Molar heat capacity	27.11 J/(mol·K)
vapor pressure (extrapolated) P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 2005 2208 2458 2772 3178 3726
Atomic properties
Oxidation states	3, 2, 1 ​(a strongly basic oxide)
Electronegativity	Pauling scale: 1.10
Ionization energies	1st: 538.1 kJ/mol 2nd: 1067 kJ/mol 3rd: 1850.3 kJ/mol
Atomic radius	empirical: 187 pm
Covalent radius	207±8 pm
Miscellanea
Crystal structure	​double hexagonal close-packed (dhcp)
Speed of sound thin rod	2475 m/s (at 20 °C)
Thermal expansion	α, poly: 12.1 µm/(m·K) (at r.t.)
Thermal conductivity	13.4 W/(m·K)
Electrical resistivity	α, poly: 615 nΩ·m (at r.t.)
Magnetic ordering	paramagnetic
Young's modulus	α form: 36.6 GPa
Shear modulus	α form: 14.3 GPa
Bulk modulus	α form: 27.9 GPa
Poisson ratio	α form: 0.280
Mohs hardness	2.5
Vickers hardness	360–1750 MPa
Brinell hardness	350–400 MPa
CAS Number	7439-91-0
History
Discovery	Carl Gustaf Mosander (1838)
Most stable isotopes of lanthanum
iso NA half-life DM DE (MeV) DP 137La syn 6×104 y ε 0.600 137Ba 138La 0.090% 1.05×1011 y ε 1.737 138Ba β− 1.044 138Ce 139La 99.910% – (SF) <38.944
Decay modes in parentheses are predicted, but have not yet been observed

References

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