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Samarium - Sm General Information Discovery Samarium was discovered by P.E. Lecoq de Boisbaudran in 1879 in Paris. Appearance Samarium is a silvery-white metal with a bright sheen. Source Samarium is found along with other rare earth metals in several minerals, the principal ones being monazite and bastnaesite. It can be separated from the other components of the mineral by ion exchange and solvent extraction. Recently, electrochemical deposition using lithium citrate as the electrolyte and a mercury electrode has been used to separate samarium from other rare earth elements. Samarium can also be produced by reducing the oxide with barium. Uses Samarium is used to dope calcium fluoride crystals for use in optical lasers. It is also used in infrared absorbing glass and as a neutron absorber in nuclear reactors. In common with other rare earth elements, samarium is used in carbon arc lighting for studio lighting and projection. Biological Role Samarium has no known biological role, and has low toxicity. General Information Samarium is relatively stable in dry air but an oxide coating forms in moist air. The metal ignites in air at 150K. |
| Physical Information | |||
| Atomic Number | 62 | ||
| Relative Atomic Mass (12C=12.000) | 150.36 | ||
| Melting Point/K | 1350 | ||
| Boiling Point/K | 2064 | ||
| Density/kg m-3 | 7520 (293K) | ||
| Ground State Electron Configuration | [Xe]4f66s2 | ||
| Electron Affinity(M-M-)/kJ mol-1 | 50 |
| Key Isotopes | ||||||
| nuclide | 144Sm | 146Sm | 147Sm | 148Sm | 149Sm | |
| atomic mass | 143.9 | 145.9 | 146.9 | 147.9 | 148.9 | |
| natural abundance | 3.1% | 0% | 15.1% | 11.3% | 13.9% | |
| half-life | stable | 7x107 yrs | 1.05x1011 yrs | 12x1014 yrs | 1x1015 yrs | |
| nuclide | 150Sm | 152Sm | 153Sm | 154Sm | ||
| atomic mass | 149.9 | 151.9 | 153.9 | |||
| natural abundance | 7.4% | 26.6% | 0% | 22.6% | ||
| half-life | stable | stable | 46.8 h | stable | ||
| Other Information | ||
| Enthalpy of Fusion/kJ mol-1 | 10.9 | |
| Enthalpy of Vaporisation/kJ mol-1 | 164.8 | |
| Oxidation States | ||
| main | SmIII | |
| others | SmII | |
| Covalent Bonds /kJ mol-1 | ||
| not applicable | ||
| Ionisation Energies/kJ mol-1 | ||
| M - M+ | 543.3 | |
| M+ - M2+ | 1068 | |
| M2+ - M3+ | 2260 | |
| M3+ - M4+ | 3990 | |
| M4+ - M5+ | ||
| M5+ - M6+ | ||
| M6+ - M7+ | ||
| M7+ - M8+ | ||
| M8+ - M9+ | ||
| M9+ - M10+ | ||
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