Samarium

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Samarium is a chemical element with the symbol Sm and atomic number 62. Samarium is a rare earth metal, with a bright silver luster, that is reasonably stable in air; it ignites in air at 150 °C. Even with long-term storage under mineral oil, samarium is gradually oxidized, with a grayish-yellow powder of the oxide-hydroxide being formed. Three crystal modifications of the metal also exist, with transformations at 734 and 922 °C.

 

General
Name, Symbol, Number samarium, Sm, 62
Chemical series lanthanides
Group, Period, Block n/a, 6, f
Appearance silvery white
Standard atomic weight 150.36(2) g·mol-1
Electrons per shell 2, 8, 18, 24, 8, 2
Physical properties
Phase solid
Density (near r.t.) 7.52 g·cm−3
Liquid density at m.p. 7.16 g·cm−3
Melting point 1345K
(1072°C, 1962°F)
Boiling point 2067K
(1794°C, 3261°F)
Heat of fusion 8.62 kJ·mol-1
Heat of vaporization 165 kJ·mol-1
Heat capacity (25°C) 29.54 J·mol-1·K-1
Vapor pressure
P(Pa) 1 10 100 1 k 10 k 100 k
at T(K) 1001 1106 1240 (1421) (1675) (2061)
Atomic properties
Crystal structure rhombohedral
Oxidation states 3
(mildly basic oxide)
Electronegativity 1.17 (Pauling scale)
Ionization energies
(more)
1st: 544.5 kJ·mol-1
2nd: 1070 kJ·mol-1
3rd: 2260 kJ·mol-1
Atomic radius 185 pm
Atomic radius (calc.) 238 pm
Miscellaneous
Magnetic ordering antiferromagnetic
Electrical resistivity (r.t.) (α, poly) 0.940 µΩ·m
Thermal conductivity (300K) 13.3 W·m-1·K-1
Thermal expansion (r.t.) (α, poly)
12.7 µm/(m·K)
Speed of sound (thin rod) (20 °C) 2130 m/s
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 412 MPa
Brinell hardness 441 MPa
CAS registry number 7440-19-9

 

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