Samarium

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, ₆₂Sm

Samarium
Pronunciation	/səˈmɛəriəm/ ​(sə-MAIR-ee-əm)
Appearance	sillery white
Standard atomic weight Ar, std(Sm)	7002150360000000000♠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 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 (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 (β−β−) 154Gd
Decay modes in parentheses are predictit, but hae nae yet been observed
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References

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.