Samarium

  • samarium, 62sm
    samarium-2.jpg
    samarium
    pronunciationm/ (mair-ee-əm)
    appearancesilvery white
    standard atomic weight ar, std(sm)150.36(2)[1]
    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
    promethiumsamariumeuropium
    atomic number (z)62
    groupgroup n/a
    periodperiod 6
    blockf-block
    element category  lanthanide
    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)
    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 states0,[2] +1, +2, +3 (a mildly basic oxide)
    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 structurerhombohedral
    rhombohedral crystal structure for samarium
    speed of sound thin rod2130 m/s (at 20 °c)
    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[3]
    magnetic susceptibility+1860.0·10−6 cm3/mol (291 k)[4]
    young's modulusα form: 49.7 gpa
    shear modulusα form: 19.5 gpa
    bulk modulusα form: 37.8 gpa
    poisson ratioα form: 0.274
    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)
    main isotopes of samarium
    iso­tope abun­dance half-life (t1/2) decay mode pro­duct
    144sm 3.08% stable
    145sm syn 340 d ε 145pm
    146sm syn 6.8×107 y α 142nd
    147sm 15.00% 1.06×1011 y α 143nd
    148sm 11.25% 7×1015 y α 144nd
    149sm 13.82% stable
    150sm 7.37% stable
    151sm syn 90 y β 151eu
    152sm 26.74% stable
    153sm syn 46.284 h β 153eu
    154sm 22.74% stable
    | references

    samarium is a chemical element with the 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 assumes 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. the last compound is a common reducing agent in chemical synthesis. samarium has no significant biological role but is only slightly toxic.

    samarium was discovered in 1879 by the french chemist paul-Émile lecoq de boisbaudran and named after the mineral samarskite from which it was isolated. the mineral itself was earlier named after a russian mine official, colonel vassili samarsky-bykhovets, who thereby became the first person to have a chemical element named after him, albeit indirectly. although classified as a rare-earth element, samarium is the 40th most abundant element in the earth's crust and is more common than metals such as tin. samarium occurs with 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 major commercial application of samarium is in samarium–cobalt magnets, 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 magnetic properties, due to the alloy's higher curie point. the radioactive isotope samarium-153 is the active component of the drug samarium (153sm) lexidronam (quadramet), which kills cancer cells in the treatment of lung cancer, prostate cancer, breast cancer and osteosarcoma. another isotope, samarium-149, is a strong neutron absorber and is therefore added to the control rods of nuclear reactors. it is also formed as a decay product during the reactor operation and is one of the important factors considered in the reactor design and operation. other applications of samarium include catalysis of chemical reactions, radioactive dating and x-ray lasers.

  • physical properties
  • chemical properties
  • compounds
  • isotopes
  • history
  • occurrence and production
  • applications
  • biological role
  • references
  • bibliography
  • external links

Samarium, 62Sm
Samarium-2.jpg
Samarium
Pronunciationm/ (MAIR-ee-əm)
Appearancesilvery white
Standard atomic weight Ar, std(Sm)150.36(2)[1]
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
promethiumsamariumeuropium
Atomic number (Z)62
Groupgroup n/a
Periodperiod 6
Blockf-block
Element category  Lanthanide
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)
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 states0,[2] +1, +2, +3 (a mildly basic oxide)
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 structurerhombohedral
Rhombohedral crystal structure for samarium
Speed of sound thin rod2130 m/s (at 20 °C)
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[3]
Magnetic susceptibility+1860.0·10−6 cm3/mol (291 K)[4]
Young's modulusα form: 49.7 GPa
Shear modulusα form: 19.5 GPa
Bulk modulusα form: 37.8 GPa
Poisson ratioα form: 0.274
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)
Main isotopes of samarium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
144Sm 3.08% stable
145Sm syn 340 d ε 145Pm
146Sm syn 6.8×107 y α 142Nd
147Sm 15.00% 1.06×1011 y α 143Nd
148Sm 11.25% 7×1015 y α 144Nd
149Sm 13.82% stable
150Sm 7.37% stable
151Sm syn 90 y β 151Eu
152Sm 26.74% stable
153Sm syn 46.284 h β 153Eu
154Sm 22.74% stable
| references

Samarium is a chemical element with the 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 assumes 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. The last compound is a common reducing agent in chemical synthesis. Samarium has no significant biological role but is only slightly toxic.

Samarium was discovered in 1879 by the French chemist Paul-Émile Lecoq de Boisbaudran and named after the mineral samarskite from which it was isolated. The mineral itself was earlier named after a Russian mine official, Colonel Vassili Samarsky-Bykhovets, who thereby became the first person to have a chemical element named after him, albeit indirectly. Although classified as a rare-earth element, samarium is the 40th most abundant element in the Earth's crust and is more common than metals such as tin. Samarium occurs with 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 major commercial application of samarium is in samarium–cobalt magnets, 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 magnetic properties, due to the alloy's higher Curie point. The radioactive isotope samarium-153 is the active component of the drug samarium (153Sm) lexidronam (Quadramet), which kills cancer cells in the treatment of lung cancer, prostate cancer, breast cancer and osteosarcoma. Another isotope, samarium-149, is a strong neutron absorber and is therefore added to the control rods of nuclear reactors. It is also formed as a decay product during the reactor operation and is one of the important factors considered in the reactor design and operation. Other applications of samarium include catalysis of chemical reactions, radioactive dating and X-ray lasers.