Samarium
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
- ↑Sm ↓ Pu
promethium ← samarium → europium
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 samarium Ither 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
Isotope
Abundance
Hauf-life (t 1/2 )
Decay mode
Product
144 Sm
3.07%
-
(β+β+)
144Nd
(α)
140Nd
145 Sm
syn
340 d
ε
145Pm
146 Sm
trace
1.03×108 y
α
142Nd
147 Sm
14.99%
1.06×1011 y
α
143Nd
148 Sm
11.24%
7×1015 y
α
144Nd
149 Sm
13.82%
>2×1015 y
(α)
145Nd
150 Sm
7.38%
-
(α)
146Nd
151 Sm
syn
90 y
β−
151Eu
152 Sm
26.75%
-
(α)
148Nd
153 Sm
syn
46.284 h
β−
153Eu
154 Sm
22.75%
>2.3×1018 y
(β−β−)
154Gd
Decay modes in parentheses are predictit, but hae nae yet been observed | references
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.
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.
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