Samarium is a chemical element wi seembol Sm an atomic nummer 62. It is a moderately haird sillery metal that readily oxidizes in air. Bein a teepical member o the lanthanide series, samarium uisually assumes the oxidation state +3. Compoonds o samarium(II) are an aa kent, maist notably the monoxide SmO, monochalcogenides SmS, SmSe an SmTe, as well as samarium(II) iodide. The last compoond is a common reducin agent in chemical synthesis. Samarium haes na signeeficant biological role an is anly slichtly toxic.

Samarium, 62Sm
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Samarium
Pronunciation/səˈmɛəriəm/ (sə-MAIR-ee-əm)
Appearancesillery white
Standard atomic weight Ar, std(Sm)150.36(2)[1]
Samarium in the periodic cairt
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 Airn Cobalt Nickel Capper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Siller (element) 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 Gowd Mercur (element) Thallium Leid (element) 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 Ununtrium Flerovium Ununpentium Livermorium Ununseptium Ununoctium
-

Sm

Pu
promethiumsamariumeuropium
Atomic nummer (Z)62
Groupgroup n/a
Periodperiod 6
Blockf-block
Element category  Lanthanide
Electron confeeguration[Xe] 4f6 6s2
Electrons per shell2, 8, 18, 24, 8, 2
Pheesical properties
Phase at STPsolit
Meltin pynt1345 K ​(1072 °C, ​1962 °F)
Bylin pynt2067 K ​(1794 °C, ​3261 °F)
Density (near r.t.)7.52 g/cm3
when liquid (at m.p.)7.16 g/cm3
Heat o fusion8.62 kJ/mol
Heat o vapourisation165 kJ/mol
Molar heat capacity29.54 J/(mol·K)
Vapour pressur
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
Atomic radiusempirical: 180 pm
Covalent radius198±8 pm
Colour lines in a spectral range
Spectral lines o samarium
Ither properties
Naitural occurrenceprimordial
Creestal structurrhombohedral
Rhombohedral creestal structur for samarium
Speed o soond 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 µ Ω·m
Magnetic orderinparamagnetic[3]
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 haurdness412 MPa
Brinell haurdness441 MPa
CAS Nummer7440-19-9
History
DiskiveryLecoq de Boisbaudran (1879)
First isolationLecoq de Boisbaudran (1879)
Main isotopes o samarium
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct
144Sm 3.07% - (β+β+) 144Nd
(α) 140Nd
145Sm syn 340 d ε 145Pm
146Sm trace 1.03×108 y α 142Nd
147Sm 14.99% 1.06×1011 y α 143Nd
148Sm 11.24% 7×1015 y α 144Nd
149Sm 13.82% >2×1015 y (α) 145Nd
150Sm 7.38% - (α) 146Nd
151Sm syn 90 y β 151Eu
152Sm 26.75% - (α) 148Nd
153Sm syn 46.284 h β 153Eu
154Sm 22.75% >2.3×1018 y (ββ) 154Gd
Decay modes in parentheses are predictit, but hae nae yet been observed
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ReferencesEedit

  1. Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
  2. Yttrium and all lanthanides except Ce, Pm, Eu, Tm, 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.
  3. Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.