Samarium
lanthanideProperties
| Property | Value |
|---|---|
| Atomic Mass | 150.36 amu |
| Category | lanthanide |
| Period | 6 |
| Electron Configuration | [Xe] 4f6 6s2 |
| Electronegativity | 1.17 (Pauling) |
| Oxidation States | 2, 3 |
| Melting Point | 1345 K (1071.8 °C) |
| Boiling Point | 2067 K (1793.8 °C) |
| Density | 7.52 g/cm³ |
| Discovered By | Lecoq de Boisbaudran (1879) |
About Samarium
Samarium is a silvery lanthanide that holds a small piece of nomenclature history: it was the first element named (indirectly) after a real person — Colonel Vasili Samarsky-Bykhovets, via the mineral samarskite. Chemically it mostly behaves as Sm(III), but it also has a stable Sm(II) state, which is rare among lanthanides and gives organic chemists samarium(II) iodide — Kagan's reagent — for single-electron pinacol couplings and Barbier-type reductions. Industrially the headline application is the SmCo₅ and Sm₂Co₁₇ permanent magnets, the first rare-earth magnets ever commercialised; their Curie temperature near 720-820 °C lets them keep magnetisation in jet-engine actuators and traveling-wave tubes where Nd₂Fe₁₄B would demagnetise. In nuclear reactors, ¹⁴⁹Sm is a heavyweight thermal-neutron poison with a cross-section around 41,000 barns, so reactor physicists track its buildup almost as carefully as xenon-135. In medicine, ¹⁵³Sm-EDTMP is injected for palliating bone-metastasis pain because its β-emission concentrates wherever bone turnover is high.
Fun Fact
Samarium was the first element ever named after a person — Colonel Vasili Samarsky-Bykhovets, a Russian mining official who gave chemists access to the mineral samples from which samarium was eventually isolated.
Common Uses
- SmCo permanent magnets for jet engine actuators and aerospace motors
- Samarium(II) iodide (Kagan's reagent) for one-electron organic reductions
- Sm-153 EDTMP injection for palliation of metastatic bone pain
- Sm-149 burnup analysis in thermal nuclear reactor cores
- Infrared-absorbing optical glass for laser and sensor windows
- Doped calcium fluoride crystals for solid-state laser hosts