Samarium Facts - Sm or Element 62

Interesting Facts About the Element Samarium

Samarium (Sm) is a lanthanide and rare earth element.
Samarium (Sm) is a lanthanide and rare earth element. Science Picture Co / Getty Images

Samarium or Sm is a rare earth element or lanthanide with atomic number 62. Like other elements in the group, it is a shiny metal under ordinary conditions. Here is a collection of interesting samarium facts, including its uses and properties:

Samarium Properties, History, and Uses

  • Samarium was the first element to be named in honor of a person (an element eponym). It was discovered in 1879 by French chemist Paul Émile Lecoq de Boisbaudran after he added ammonium hydroxide to preparation made from the mineral samarskite. Samarskite gets its name from its discoverer and the man who loaned Boisbaudran the mineral samples for his study -- Russian mining engineer V.E. Samarsky-Bukjovets.
  • Ingesting the right dose of samarium chloride will allow it to bind with alcohol and prevent you from getting intoxicated.
  • It's unknown exactly how toxic samarium is. Its insoluble compounds are considered non-toxic, while the soluble salts may be mildly poisonous. There is some evidence samarium helps stimulate metabolism. It is not an essential element for human nutrition. When salts of samarium are ingested, only about 0.05% of the element is absorbed, while the rest is immediately excreted. Of the absorbed metal, about 45% goes to the liver and 45% is deposited onto bone surfaces. The remainder of the absorbed metal is eventually excreted. The samarium on bones remains in the body for around 10 years.
  • Samarium is a yellowish silver-colored metal. It is the hardest and the most brittle of the rare earth elements. It tarnishes in air and will ignite in air at about 150 °C. Under ordinary conditions, the metal has rhombohedral crystals. Heating changes the crystal structure to hexagonal close-packed (hcp). Further heating leads to a transition to a body-centered cubic (bcc) phase.
  • Natural samarium consists of a mixture of 7 isotopes. Three of these isotopes are unstable, but have long half-lives. A total of 30 isotopes have been discovered or prepared, with atomic masses ranging from 131 to 160.
  • There are numerous uses for this element. It is used to make samarium-cobalt permanent magnets, samarium X-ray lasers, glass that absorbs infrared light, a catalyst for ethanol production, in the manufacture of carbon lights, and as part of a pain treatment regimen for bone cancer. Samarium may be used as an absorber in nuclear reactors. Nanocrystalline BaFCl:Sm3+ is a highly sensitive x-ray storage phosphor, which may have applications in dosimetry and medical imaging. Samarium hexaboride, SmB6, is a topological insulator that may find use in quantum computers.
  • In 1979, Sony introduced the first portable cassette player, the Sony Walkman, made using samarium cobalt magnets.
  • Samarium is never found free in nature. It occurs in minerals with other rare earths. Sources of the element include the minerals monazite and bastnasite. It is also found in samarskite, orthite, cerite, fluorspar, and ytterbite. Samarium is recovered from monazite and bastnasite using ion exchange and solvent extraction. Electrolysis may be used to produce pure samarium metal from its molten chloride with sodium chloride.
  • Samarium is the 40th most abundant element on Earth. The average concentration of samarium in the Earth's crust is 6 parts per million and about 1 part per billion by weight in the solar system. The element's concentration in seawater varies, ranging from 0.5 to 0.8 parts per trillion. Samarium is not homogeneously distributed in soil. For example, sandy soil may have a samarium concentration 200 times higher at the surface as compared with deeper, damp layers. In clay soil, there may be over a thousand times more samarium at the surface than further down.
  • The most common oxidation state of samarium is +3 (trivalent). Most samarium salts are pale yellow in color.
  • An approximate cost of pure samarium is about $360 per 100 grams of metal.

Samarium Atomic Data

Element Name: Samarium

Atomic Number: 62

Symbol: Sm

Atomic Weight: 150.36

Discovery: Boisbaudran 1879 or Jean Charles Galissard de Marignac 1853 (both of France)

Electron Configuration: [Xe] 4f6 6s2

Element Classification: rare earth (lanthanide series)

Name Origin: named for the mineral samarskite.

Density (g/cc): 7.520

Melting Point (°K): 1350

Boiling Point (°K): 2064

Appearance: silvery metal

Atomic Radius (pm): 181

Atomic Volume (cc/mol): 19.9

Covalent Radius (pm): 162

Ionic Radius: 96.4 (+3e)

Specific Heat (@20°C J/g mol): 0.180

Fusion Heat (kJ/mol): 8.9

Evaporation Heat (kJ/mol): 165

Debye Temperature (°K): 166.00

Pauling Negativity Number: 1.17

First Ionizing Energy (kJ/mol): 540.1

Oxidation States: 4, 3, 2, 1 (usually 3)

Lattice Structure: rhombohedral

Lattice Constant (Å): 9.000

Uses: alloys, magnets in headphones

Source: monazite (phosphate), bastnesite

References and Historical Papers

Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110.

De Laeter, J. R.; Böhlke, J. K.; De Bièvre, P.; et al. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. IUPAC. 75 (6): 683–800.

Boisbaudran, Lecoq de (1879). Recherches sur le samarium, radical d'une terre nouvelle extraite de la samarskite. Comptes rendus hebdomadaires des séances de l'Académie des sciences89: 212–214.