Samarium (Sm)
Soft silvery metallic element, belongs to the lanthanoids. Seven natural isotopes, Sm-147 is the only radioisotope, and has a half-life of 2.5*10^11 years. Used for making special alloys needed in the production of nuclear reactors. Also used as a neutron absorber. Small quantities of samarium oxide is used in special optical glasses. The largest use of the element is its ferromagnetic alloy which produces permanent magnets that are five times stronger than magnets produced by any other material. Discovered by Francois Lecoq de Boisbaudran in 1879.
| Atomic Number | 62 |
|---|---|
| Atomic Weight | 150.36 |
| Mass Number | 152 |
| Group | |
|---|---|
| Period | 6 |
| Block | f |
| Protons | 62 p+ |
|---|---|
| Neutrons | 90 n0 |
| Electrons | 62 e- |
Properties
| Atomic Radius | 185 pm
|
|---|---|
| Atomic Volume | 19.9 cm³/mol
|
| Covalent Radius | 172 pm
|
| Metallic Radius | |
| Ionic Radius | 122 pm
|
| Crystal Radius | 136 pm
|
| Van der Waals radius |
236 pm
|
| Density | 7.52 g/cm³
|
| Boiling Point | 2,064 K
|
| Melting Point | 1,350 K
|
| Electrons per shell | 2, 8, 18, 24, 8, 2 |
| Electronegativity |
1.17
|
| Electrophilicity | |
| Proton Affinity | |
| Electron Affinity | |
| Ionization Potential | 5.64371 eV/particle
|
| Heat of Vaporization | 165 kJ/mol
|
| Heat of Fusion | 8.9 kJ/mol
|
| Heat of Formation | 206.7 kJ/mol
|
| Molar Heat Capacity | 29.54 J/(mol K)
|
| Specific Heat Capacity | 0.197 J/(g⋅K)
|
| Thermal Conductivity | |
| Gas Basicity | |
| Dipole Polarizability | 192 a₀
|
| C6 Dispersion Coefficient | |
| Oxidation States | 2, 3 |
| Color | Silver
|
| Crystal Structure | Simple Trigonal (RHL) |
| Lattice Constant | 9 Å
|
| Bulk Modulus | |
| Electrical Resistivity | |
| Electron Configuration | [Xe] 4f6 6s2 |
| Magnetic Ordering | |
| Magnetic Susceptibility | |
| Phase | Solid |
| Poisson Ratio | |
| Shear Modulus | |
| Young's Modulus | |
| Allotropes | |
| Alternate Names | |
| Adiabatic Index | |
| Appearance | |
| Electric Conductivity | |
| Critical Pressure | |
| Critical Temperature | |
| Curie Point | |
| Electrical | |
| Hardness | |
| Magnetic Susceptibility | |
| Magnetic | |
| Neel Point | |
| Neutron Cross Section | |
| Neutron Mass Absorption | |
| Gas Phase | |
| Quantum Numbers | |
| Refractive Index | |
| Space Group | |
| Speed of Sound | |
| Superconducting Point | |
| Thermal Expansion | |
| Valence Electrons | |
| Classification | |
| Category | Lanthanides, Lanthanides |
| CAS Group | |
| IUPAC Group | |
| Glawe Number | 27 |
| Mendeleev Number | 23 |
| Pettifor Number | 28 |
| Geochemical Class | rare earth & related |
| Goldschmidt Class | litophile |
| Radioactivity | |
| Radioactive | No |
| Decay Mode | |
| Half-Life | |
| Lifetime | |
| Abundance | |
| Abundance in Earth's crust | 7.05 mg/kg
|
| Abundance in Oceans | 0.00000045 mg/L
|
| Abundance in Human Body | |
| Abundance in Meteor | |
| Abundance in Sun | |
| Abundance in Universe | 5×10-7% |
Isotopes of Samarium
Stable Isotopes
144Sm 147Sm 148Sm 149Sm 150Sm 152Sm 154Sm
Unstable Isotopes
128Sm 129Sm 130Sm 131Sm 132Sm 133Sm 134Sm 135Sm 136Sm 137Sm 138Sm 139Sm 140Sm 141Sm 142Sm 143Sm 145Sm 146Sm 151Sm 153Sm 155Sm 156Sm 157Sm 158Sm 159Sm 160Sm 161Sm 162Sm 163Sm 164Sm 165Sm
History
In 1853, Jean Charles Galissard de Marignac discovered samarium when he found lines in mineral spectra. Paul Émile Lecoq de Boisbaudran isolated a samarium salt in Paris in 1879 from the mineral samarskite and identified a new element in it via sharp optical absorption lines. The pure element was produced only in 1901 by Eugène-Anatole Demarçay. From samarskite, a mineral named after Russian mine official, Col. Samarski
| Discoverers | Paul Émile Lecoq de Boisbaudran |
|---|---|
| Discovery Location | France |
| Discovery Year | 1879 |
| Name Origin | Named after the mineral samarskite. |
Samarium is considered to be moderately toxic
Samarium metal can be produced by reducing the oxide with lanthanum
Uses
Samarium's main use is in samarium-cobalt alloy magnets for headphones, small motors and pickups for some electric guitars. Radioactive samarium-153 is used to kill cancer cells in the treatment of lung cancer, prostate cancer, breast cancer and osteosarcoma. Samarium and its compounds are also used as catalyst and chemical reagent. 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.
Sources
Found with other rare earths in monazite sand. The sand is often 50% rare earths by weight and 2.8% samarium.