Samarium Element Facts / Chemistry


Rare earth oxides

Clockwise from top center: Rare earth oxides of praseodymium, cerium, lanthanum, neodymium, samarium and gadolinium. Image Ref.(4)

62
Sm
150.4

Data Zone

Classification: Samarium is a lanthanide and rare earth metal
Color: silvery-white
Atomic weight: 150.4
State: solid
Melting point: 1170 oC, 1443 K
Boiling point: 1790 oC, 2063 K
Electrons: 62
Protons: 62
Neutrons in most abundant isotope: 90
Electron shells: 2,8,18,24,8,2
Electron configuration: [Xe] 4f6 6s2
Density @ 20oC: 7.54 g/cm3
Show more, including: Heats, Energies, Oxidation, Reactions, Compounds, Radii, Conductivities
Atomic volume: 20.0 cm3/mol
Structure: close packed (ABCBCACAB)
Specific heat capacity 0.20 J g-1 K-1
Heat of fusion 8.62 kJ mol-1
Heat of atomization 207 kJ mol-1
Heat of vaporization 191.63 kJ mol-1
1st ionization energy 543.3 kJ mol-1
2nd ionization energy 1068 kJ mol-1
3rd ionization energy 2260 kJ mol-1
Electron affinity
Minimum oxidation number 0
Min. common oxidation no. 0
Maximum oxidation number 3
Max. common oxidation no. 3
Electronegativity (Pauling Scale) 1.17
Polarizability volume 28.8 Å3
Reaction with air mild, ⇒ Sm2O3
Reaction with 15 M HNO3 mild, ⇒ Sm(NO3)3
Reaction with 6 M HCl mild, ⇒ H2, SmCl3
Reaction with 6 M NaOH
Oxide(s) SmO, Sm2O3 (samaria)
Hydride(s) SmH2, SmH3
Chloride(s) SmCl2, SmCl3
Atomic radius 185 pm
Ionic radius (1+ ion)
Ionic radius (2+ ion) 136 pm
Ionic radius (3+ ion) 109.8 pm
Ionic radius (1- ion)
Ionic radius (2- ion)
Ionic radius (3- ion)
Thermal conductivity 13.3 W m-1 K-1
Electrical conductivity 1.1 x 106 S m-1
Freezing/Melting point: 1170 oC, 1443 K



Samarium uses

Samarium is used in headphones, iPods and guitar pickups.

Discovery of Samarium

Dr. Doug Stewart

In 1853, in Geneva, Switzerland, chemist Jean Charles Galissard de Marignac discovered samarium when he found lines in mineral spectra he was studying that matched no known element.

Paul-Émile Lecoq de Boisbaudran isolated a samarium salt in 1879, in Paris.

First, Boisbaudran extracted ‘didymium’ from the mineral samarskite and made a solution of ‘didymium’ nitrate. He then added ammonium hydroxide and found two precipitates were formed; one containing ‘didymium’ and the other a new element – samarium. (1),(2)

We should bear in mind that ‘didymium’ had been incorrectly identified as a new element by Carl Mosander in 1841.

‘Didymium’ was even given the symbol Di in Mendeleev’s first edition of the periodic table in 1869.

It wasn’t until 1885 that Carl Auer von Welsbach established that ‘didymium’ was actually composed of two distinct, new elements: neodymium and praseodymium.

The new element samarium was named after the mineral samarskite in which it had been found. (The mineral samarskite had been named in 1847 by mineralogist Heinrich Rose after a Russian mine official, Vasili Samarsky-Bykhovets, who had given him a sample of it.)

In addition to samarium, Lecoq discovered gallium in 1875 and he went on to isolate gadolinium in 1885 and dysprosium in 1886.

In 1901 Eugène-Antole Demarçay found that Lecoq’s samarium was impure and he successfully isolated europium magnesium nitrate from a sample of samarium magnesium nitrate. (1a)

A brief introduction to the lanthanides.

Samarium uses montage

Samarium-cobalt magnets are used in quartz watches and in camera shutters. (3)


Appearance and Characteristics

Harmful effects:

Samarium is considered to be moderately toxic.

Characteristics:

Samarium is a bright, fairly hard, silvery white metal. It is one of the lanthanide rare earth metals.

It is stable in air at normal temperatures, but ignites in air when the temperature is 150 oC or higher. In moist air it tarnishes to the oxide.

In its compounds Samarium usually exists as a trivalent ion, Sm3+. Most of its salts are pale yellow in color.

Uses of Samarium

Samarium’s main use is in samarium-cobalt alloy magnets for headphones, small motors and pickups for some electric guitars. These magnets have a high resistance to demagnetization. They keep their ferromagnetism at temperatures up to 700 oC. (3) As a result of their ability to operate at high temperatures, SmCo magnets are used in precision-guided weapons.

Samarium oxide (samaria) is used as a catalyst for the dehydration and dehydrogenation of ethanol. Samarium oxide is also used in infrared absorbing glass.

Radioactive 153Sm is used in the treatment of cancers.

Samarium is also used as an absorber in nuclear reactors.

Abundance and Isotopes

Abundance earth’s crust: 6 parts per million by weight, 0.8 parts per million by moles

Abundance solar system: 1 part per billion by weight, 10 parts per trillion by moles

Cost, pure: $360 per 100g

Cost, bulk: $ per 100g

Source: Samarium is not found free in nature but is found in a number of minerals mainly monazite and bastnaesite. Commercially, it is recovered from monazite sand and bastnaesite using ion exchange and solvent extraction techniques. Samarium metal can be produced by electrolysis of the molten chloride with sodium chloride.

Isotopes: Samarium has 30 isotopes whose half-lives are known, with mass numbers 131 to 160. Naturally occurring samarium is a mixture of seven isotopes and they are found in the percentages shown: 144Sm (3.1%), 147Sm (15.0%), 148Sm (11.2%), 149Sm (13.8%), 150Sm (7.4%), 152Sm (26.7%) and 154Sm (22.8%). The most abundant isotope is 152Sm at 26.7%.

References

1. Ferenc Szabadváry, Handbook of the Chemistry and Physics of the Rare Earths Vol. 11., Elsevier Science Publishers., 1998, p52.
1a. Ferenc Szabadváry, Handbook of the Chemistry and Physics of the Rare Earths Vol. 11., Elsevier Science Publishers., 1998, p62.
2. John Emsley, Nature’s building blocks: an A-Z guide to the elements., Oxford University Press, 2003, p372.
3. Per Enghag, Encyclopedia of the elements: technical data, history, processing, applications., John Wiley and Sons, 2004, page 485.
4. Photo: LLNL

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Comments

  1. Great info. Helped me on my project on samarium.