Atomic Properties of Sm
- Atomic Number of Sm
- 62
- Atomic Mass of Sm
- 150.3600 u
- Electron Configuration
- [Xe] 4f6 6s2
- Electronegativity
- 1.17
- Block
- f-block
- Group
- —
- Period
- 6
Samarium (Sm) is element 62 on the periodic table. Atomic mass of Sm: 150.3600 u. Sm is in period 6. Melting point of Sm: 1345.00 K.Density of Sm: 7.52 g/cm³.
Samarium in everyday life and industry
Samarium has no known biological role. Samarium-153 treats bone cancer pain.
Discovered by Paul Émile Lecoq de Boisbaudran in France, 1879
Name origin: Named after the mineral samarskite.
Silvery lanthanide with seven natural isotopes. Sm-147 is radioactive (α, t1/2 ~1.06×1011 years)—crucial for Sm-Nd geochronology. Forms SmCo5 and Sm2Co17 permanent magnets that outperform NdFeB at high temperatures. Sm-149 has an enormous neutron capture cross-section (40,000 barns), useful in reactor control. Discovered 1879 by Lecoq de Boisbaudran.
Samarium has 6 naturally occurring isotopes, plus 3 notable radioactive isotopes.
| Isotope | Atomic Mass (u) | Abundance | Half-Life | Decay Mode |
|---|---|---|---|---|
| 14462Sm (Sm-144)Samarium-144 isotope | 143.9120065 | 3.070% | — | — |
| 14662Sm (Sm-146)Samarium-146 isotope | 145.913047 | 0% | 103 million years | α |
| 14762Sm (Sm-147)Samarium-147 isotope | 146.9149044 | 14.99% | 1.06×10¹¹ years | α |
| 14862Sm (Sm-148)Samarium-148 isotope | 147.9148292 | 11.24% | — | — |
| 14962Sm (Sm-149)Samarium-149 isotope | 148.9171921 | 13.82% | — | — |
| 15062Sm (Sm-150)Samarium-150 isotope | 149.9172829 | 7.380% | — | — |
| 15262Sm (Sm-152)Samarium-152 isotope | 151.9197397 | 26.75% | — | — |
| 15362Sm (Sm-153)Samarium-153 isotope | 152.9220974 | 0% | 46.3 hours | β⁻ |
| 15462Sm (Sm-154)Samarium-154 isotope | 153.9222169 | 22.75% | — | — |
Data source: NIH PubChem (aggregated from IUPAC, NIST)
Isotopes of Samarium have important real-world applications in science and industry.
147Sm is used for determining formation ages of igneous and metamorphic rocks via analysis of the minerals which compose them, such as those shown in Fig. IUPAC.62.1 [440], [441], [442].
The radioisotope 153Sm (with a half-life of 1.9 days) is used in medicine to treat the severe pain associated with cancer that has spread to bones (Fig. IUPAC.62.2) [443], [444], [445].
It is used in the electronics and ceramics industries. It is easily magnetized and very difficult to demagnetize. This suggests important future applications in solid-state and superconductor technologies.
Found with other rare earths in monazite sand. The sand is often 50% rare earths by weight and 2.8% samarium.
Loading quiz...