Samarium

Samarium, 62Sm
Samarium
Pronunciation/səˈmɛəriəm/ ​(sə-MAIR-ee-əm)
Appearancesilvery white
Standard atomic weight Ar°(Sm)
Samarium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
–
↑
Sm
↓
Pu
promethium ← samarium → europium
Atomic number (Z)62
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 (at 20° C)7.518 g/cm3 [3]
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)
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,[4] +1,[5] +2[6]
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 (hR3)
Lattice constants
Rhombohedral crystal structure for samarium
ar = 0.89834 nm
α = 23.307°
ah = 0.36291 nm
ch = 2.6207 nm (at 20 °C)[3]
Thermal expansionpoly: 12.7 (at r.t.) µm/(m⋅K)
Thermal conductivity13.3 W/(m⋅K)
Electrical resistivityα, poly: 0.940 (at r.t.) µΩ⋅m
Magnetic orderingparamagnetic[7]
Molar magnetic susceptibility+1860.0×10−6 cm3/mol (291 K)[8]
Young's modulus49.7 GPa
Shear modulus19.5 GPa
Bulk modulus37.8 GPa
Speed of sound thin rod2130 m/s (at 20 °C)
Poisson ratio0.274
Vickers hardness410–440 MPa
Brinell hardness440–600 MPa
CAS Number7440-19-9
History
Namingafter the mineral samarskite (itself named after Vassili Samarsky-Bykhovets)
Discovery and first isolationLecoq de Boisbaudran (1879)
Isotopes of samarium
Main isotopes[9] Decay
abun­dance half-life (t1/2) mode pro­duct
144Sm 3.08% stable
145Sm synth 340 d ε 145Pm
146Sm trace 9.20×107 y[10] 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 46.2846 h β− 153Eu
154Sm 22.7% stable
 Category: Samarium
| references

Samarium is a chemical element; it has symbol Sm and atomic number 62. It is a moderately hard silvery metal that slowly oxidizes in air. Being a typical member of the lanthanide series, samarium usually has the oxidation state +3. Compounds of samarium(II) are also known, most notably the monoxide SmO, monochalcogenides SmS, SmSe and SmTe, as well as samarium(II) iodide.

Discovered in 1879 by French chemist Paul-Émile Lecoq de Boisbaudran, samarium was named after the mineral samarskite from which it was isolated. The mineral itself was named after a Russian mine official, Colonel Vassili Samarsky-Bykhovets, who thus became the first person to have a chemical element named after him, though the name was indirect.

Samarium occurs in concentration up to 2.8% in several minerals including cerite, gadolinite, samarskite, monazite and bastnäsite, the last two being the most common commercial sources of the element. These minerals are mostly found in China, the United States, Brazil, India, Sri Lanka and Australia; China is by far the world leader in samarium mining and production.

The main commercial use of samarium is in samarium–cobalt magnets,[11] which have permanent magnetization second only to neodymium magnets; however, samarium compounds can withstand significantly higher temperatures, above 700 °C (1,292 °F), without losing their permanent magnetic properties. The radioisotope samarium-153 is the active component of the drug samarium (153Sm) lexidronam (Quadramet), which kills cancer cells in lung cancer, prostate cancer, breast cancer and osteosarcoma. Another isotope, samarium-149, is a strong neutron absorber and so is added to control rods of nuclear reactors. It also forms as a decay product during the reactor operation and is one of the important factors considered in the reactor design and operation. Other uses of samarium include catalysis of chemical reactions, radioactive dating and X-ray lasers. Samarium(II) iodide, in particular, is a common reducing agent in chemical synthesis.

Samarium has no biological role; some samarium salts are slightly toxic.[12]

  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. ^ a b Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
  4. ^ Yttrium and all lanthanides except Ce and Pm 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.
  5. ^ 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 2017,? 121,? 8,? 1849–1854. 121 (8): 1849–1854. doi:10.1021/acs.jpca.7b00247. PMID 28182423. S2CID 3723987..
  6. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. ISBN 978-0-08-037941-8.
  7. ^ Lide, D. R., ed. (2005). "Magnetic susceptibility of the elements and inorganic compounds". CRC Handbook of Chemistry and Physics (PDF) (86th ed.). Boca Raton (FL): CRC Press. p. 4-134. ISBN 0-8493-0486-5.
  8. ^ Weast, Robert (1983). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E112. ISBN 978-0-8493-0464-4.
  9. ^ 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.
  10. ^ 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.
  11. ^ "Samarium (Sm) | AMERICAN ELEMENTS ®". American Elements: The Materials Science Company. Retrieved 2023-11-17.
  12. ^ Cite error: The named reference emsley was invoked but never defined (see the help page).