Samarium is a chemical element wi symbol 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, 62 Sm Samarium Pronunciation (sə-MAIR -ee-əm ) Appearance sillery white Standard atomic weight A r, std (Sm) 7002150360000000000♠ 150.36(2)[ 1] Samarium in the periodic cairt
Atomic nummer (Z ) 62 Group group n/a Period period 6 Block f-block Element category Lanthanide Electron confeeguration [Xe ] 4f6 6s2 Electrons per shell 2, 8, 18, 24, 8, 2 Pheesical properties Phase at STP solit Meltin pynt 1345 K (1072 °C, 1962 °F) Bylin pynt 2067 K (1794 °C, 3261 °F) Density (near r.t. ) 7.52 g/cm3 when liquid (at m.p. ) 7.16 g/cm3 Heat o fusion 8.62 kJ/mol Heat o vapourisation 165 kJ/mol Molar heat capacity 29.54 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 states 0,[ 2] +1, +2, +3 (a mildly basic oxide) Electronegativity Pauling scale: 1.17 Atomic radius empirical: 180 pm Covalent radius 198±8 pm Colour lines in a spectral range Spectral lines o samariumIther properties Naitural occurrence primordial Creestal structur rhombohedral Speed o soond thin rod 2130 m/s (at 20 °C) Thermal expansion (r.t. ) (α, poly) 12.7 µm/(m·K) Thermal conductivity 13.3 W/(m·K) Electrical resistivity (r.t. ) (α, poly) 0.940 µ Ω·m Magnetic orderin paramagnetic [ 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 haurdness 412 MPa Brinell haurdness 441 MPa CAS Nummer 7440-19-9 History Diskivery Lecoq de Boisbaudran (1879) First isolation Lecoq de Boisbaudran (1879) Main isotopes o samarium
Decay modes in parentheses are predictit, but hae nae yet been observed | references
↑ 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 .
↑ 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 .
↑ Magnetic susceptibility of the elements and inorganic compounds , in Handbook of Chemistry and Physics 81st edition, CRC press.