Samarium, 00Sm
Samarium
Pronunciation/səˈmɛəriəm/ (sə-MAIR-ee-əm)
Appearancesilvery white
Standard atomic weight Ar°(Sm)
Samarium in the periodic table
Groupf-block groups (no number)
Periodperiod 6
Block  f-block
Electron configuration[Xe] 4f6 6s2
Electrons per shell2, 8, 18, 24, 8, 2
Physical properties
Phase at STPsolid
Melting point1345 K (1072 °C, 1962 °F)
Boiling point2173 K (1900 °C, 3452 °F)
Density (near r.t.)7.52 g/cm3
when liquid (at m.p.)7.16 g/cm3
Heat of fusion8.62 kJ/mol
Heat of vaporization192 kJ/mol
Molar heat capacity29.54 J/(mol·K)
Specific heat capacity196.462 J/(kg·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 statescommon: +3
0,[3] +1,[4] +2[5]
ElectronegativityPauling scale: 1.17
Ionization energies
  • 1st: 544.5 kJ/mol
  • 2nd: 1070 kJ/mol
  • 3rd: 2260 kJ/mol
Atomic radiusempirical: 180 pm
Covalent radius198±8 pm
Color lines in a spectral range
Spectral lines of samarium
Other properties
Natural occurrenceprimordial
Crystal structure rhombohedral
Rhombohedral crystal structure for samarium
Thermal expansion(r.t.) (α, poly) 12.7 µm/(m⋅K)
Thermal conductivity13.3 W/(m⋅K)
Electrical resistivity(r.t.) (α, poly) 0.940 µΩ⋅m
Magnetic orderingparamagnetic[6]
Young's modulusα form: 49.7 GPa
Shear modulusα form: 19.5 GPa
Bulk modulusα form: 37.8 GPa
Speed of sound thin rod2130 m/s (at 20 °C)
Poisson ratioα form: 0.274
Vickers hardness412 MPa
Brinell hardness441 MPa
CAS Number7440-19-9
History
Discovery1879
First isolationLecoq de Boisbaudran (1879)
Isotopes of samarium
Main isotopes[7] Decay
Isotope abun­dance half-life (t1/2) mode pro­duct
144Sm 3.08% stable
145Sm synth 340 d ε 145Pm
146Sm trace 9.20×107 y[8] α 142Nd
147Sm 15% 1.066×1011 y α 143Nd
148Sm 11.3% 6.3×1015 y α 144Nd
149Sm 13.8% stable
150Sm 7.37% stable
151Sm synth 94.6 y β 151Eu
152Sm 26.7% stable
153Sm synth 46.285 h β 153Eu
154Sm 22.7% stable
 Category: Samarium
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References

  1. "Standard Atomic Weights: Samarium". CIAAW. 2005.
  2. Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  3. Yttrium and all lanthanides except Ce, Pm, Tm, and Yb have been observed in the oxidation state 0 in bis(1,3,5-tri-t-butylbenzene) complexes, see Cloke, F. Geoffrey N. (1993). "Zero Oxidation State Compounds of Scandium, Yttrium, and the Lanthanides". Chem. Soc. Rev. 22: 17–24. doi:10.1039/CS9932200017. and Arnold, Polly L.; Petrukhina, Marina A.; Bochenkov, Vladimir E.; Shabatina, Tatyana I.; Zagorskii, Vyacheslav V.; Cloke (2003-12-15). "Arene complexation of Sm, Eu, Tm and Yb atoms: a variable temperature spectroscopic investigation". Journal of Organometallic Chemistry. 688 (1–2): 49–55. doi:10.1016/j.jorganchem.2003.08.028.
  4. SmB6 cluster anion has been reported and contains Sm in rare oxidation state of +1; see Paul, J. Robinson; Xinxing, Zhang; Tyrel, McQueen; Kit, H. Bowen; Anastassia, N. Alexandrova (2017). "SmB6 Cluster Anion: Covalency Involving f Orbitals". J. Phys. Chem. A. 121 (8): 1849–1854. Bibcode:2017JPCA..121.1849R. doi:10.1021/acs.jpca.7b00247. PMID 28182423. S2CID 3723987..
  5. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. doi:10.1016/C2009-0-30414-6. ISBN 978-0-08-037941-8.
  6. Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.
  7. Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3) 030001. doi:10.1088/1674-1137/abddae.
  8. Chiera, Nadine M.; Sprung, Peter; Amelin, Yuri; Dressler, Rugard; Schumann, Dorothea; Talip, Zeynep (1 August 2024). "The 146Sm half-life re-measured: consolidating the chronometer for events in the early Solar System". Scientific Reports. 14 (1). doi:10.1038/s41598-024-64104-6. PMC 11294585.