Template:Infobox samarium

Samarium,  ₆₂Sm

General properties
Name, symbol	samarium, Sm
Appearance	silvery white
Allotropes	α form
Pronunciation	/səˈmɛəriəm/ sə-MAIR-ee-əm
Samarium in the periodic table
– ↑ Sm ↓ Pu promethium ← samarium → europium
Atomic number (Z)	62
Group, block	group n/a, f-block
Period	period 6
Element category	lanthanide
Standard atomic weight (±) (Ar)	150.36(2)
Electron configuration	[Xe] 4f6 6s2
per shell	2, 8, 18, 24, 8, 2
Physical properties
Phase	solid
Melting point	1345 K ​(1072 °C, ​1962 °F)
Boiling point	2173 K ​(1900 °C, ​3452 °F)
Density near r.t.	7.52 g/cm3
when liquid, at m.p.	7.16 g/cm3
Heat of fusion	8.62 kJ/mol
Heat of vaporization	192 kJ/mol
Molar heat capacity	29.54 J/(mol·K)
vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 1001 1106 1240 (1421) (1675) (2061)
Atomic properties
Oxidation states	4, 3, 2, 1 ​(a mildly basic oxide)
Electronegativity	Pauling scale: 1.17
Ionization energies	1st: 544.5 kJ/mol 2nd: 1070 kJ/mol 3rd: 2260 kJ/mol
Atomic radius	empirical: 180 pm
Covalent radius	198±8 pm
Miscellanea
Crystal structure	​rhombohedral
Speed of sound thin rod	2130 m/s (at 20 °C)
Thermal expansion	(r.t.) (α, poly) 12.7 µm/(m·K)
Thermal conductivity	13.3 W/(m·K)
Electrical resistivity	(r.t.) (α, poly) 0.940 µΩ·m
Magnetic ordering	paramagnetic
Young's modulus	α form: 49.7 GPa
Shear modulus	α form: 19.5 GPa
Bulk modulus	α form: 37.8 GPa
Poisson ratio	α form: 0.274
Vickers hardness	410–440 MPa
Brinell hardness	440–600 MPa
CAS Number	7440-19-9
History
Naming	after the mineral samarskite (itself named after Vasili Samarsky-Bykhovets)
Discovery and first isolation	Lecoq de Boisbaudran (1879)
Most stable isotopes of samarium
iso NA half-life DM DE (MeV) DP 144Sm 3.07% – (β+β+) 1.7811 144Nd (α) 0.0761 140Nd 145Sm syn 340 d ε – 145Pm 146Sm trace 1.03×108 y α 2.529 142Nd 147Sm 14.99% 1.06×1011 y α 2.310 143Nd 148Sm 11.24% 7×1015 y α 1.986 144Nd 149Sm 13.82% >2×1015 y (α) 1.870 145Nd 150Sm 7.38% – (α) 1.4495 146Nd 151Sm syn 90 y β− – 151Eu 152Sm 26.75% – (α) 0.2203 148Nd 153Sm syn 46.284 h β− – 153Eu 154Sm 22.75% >2.3×1018 y (β−β−) 1.2510 154Gd
Decay modes in parentheses are predicted, but have not yet been observed

References

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