Samarium: the essentials
Samarium has a bright silver lustre and is reasonably stable in air. It ignites in air at 150°C. It is a rare earth metal. It is found with other rare earth elements in minerals including monazite and bastnaesite and is used in electronics industries.
- Name: samarium
- Symbol: Sm
- Atomic number: 62
- Relative atomic mass (Ar): 150.36 (2) [see note g]
- Standard state: solid at 298 K
- Colour: silvery white
- Classification: Metallic
- Group in periodic table:
- Group name: Lanthanoid
- Period in periodic table: 6 (lanthanoid)
- Block in periodic table: f-block
- Electron shell structure: 2.8.18.24.8.2
- CAS Registry ID: 7440-19-9
This sample is from The Elements Collection, an attractive and safely packaged collection of the 92 naturally occurring elements that is available for sale.
Samarium: historical information
Samarium was discovered spectroscopically by its sharp absorption lines in 1853 by Jean Charles Galissard de Marignac in an "earth" called didymia. The element was isolated in 1879 by Lecoq de Boisbaudran from the mineral samarskite, named in honour of a Russian mine official, Colonel Samarski, and which therefore gave samarium its name.
Samarium around us Read more »
Samarium has no biological role but is said to stimulate the metabolism.
Samarium is never found in nature as the free element. Samarium is found in the ores monazite sand [(Ce, La, etc.)PO4] and bastn°site [(Ce, La, etc.)(CO3)F], ores containing small amounts of all the rare earth metals. It is difficult to separate from other rare earth elements.
| Location | ppb by weight | ppb by atoms | Links |
|---|---|---|---|
| Universe | 5 | 0.04 | 
|
| Crustal rocks | 6000 | 820 | 
|
| Human | (no data) ppb by weight | (no data) atoms relative to C = 1000000 | 
|
Physical properties Read more »
Density of solid: 7353 kg m-3
Molar volume: |196| cm3
Thermal conductivity: |206| W m‑1 K‑1
Heat properties Read more »
Melting point: 1345 [1072 °C (1962 °F)] K
Boiling point: 2076 [1803 °C (3277 °F)] K
Enthalpy of fusion: |203| kJ mol-1
Crystal structure Read more »
The solid state structure of samarium is: trigonal.
Samarium: orbital properties Read more »
Samarium atoms have 62 electrons and the shell structure is 2.8.18.24.8.2. The ground state electronic configuration of neutral Samarium is [Xe].4f6.6s2 and the term symbol of Samarium is 7F0.
Pauling electronegativity: 1.17 (Pauling units)
First ionisation energy: 544.5 kJ mol‑1
Second ionisation energy: 1070 kJ mol‑1
Isolation
Isolation: samarium metal is available commercially so it is not normally necessary to make it in the laboratory, which is just as well as it is difficult to isolate as the pure metal. This is largely because of the way it is found in nature. The lanthanoids are found in nature in a number of minerals. The most important are xenotime, monazite, and bastnaesite. The first two are orthophosphate minerals LnPO4 (Ln deonotes a mixture of all the lanthanoids except promethium which is vanishingly rare) and the third is a fluoride carbonate LnCO3F. Lanthanoids with even atomic numbers are more common. The most comon lanthanoids in these minerals are, in order, cerium, lanthanum, neodymium, and praseodymium. Monazite also contains thorium and ytrrium which makes handling difficult since thorium and its decomposition products are radioactive.
For many purposes it is not particularly necessary to separate the metals, but if separation into individual metals is required, the process is complex. Initially, the metals are extracted as salts from the ores by extraction with sulphuric acid (H2SO4), hydrochloric acid (HCl), and sodium hydroxide (NaOH). Modern purification techniques for these lanthanoid salt mixtures are ingenious and involve selective complexation techniques, solvent extractions, and ion exchange chromatography.
Pure samarium is available through the electrolysis of a mixture of molten SmCl3 and NaCl (or CaCl2) in a graphite cell which acts as cathode using graphite as anode. The other product is chlorine gas.
Samarium isotopes Read more »
Samarium isotopes are used in various applications. Sm-144 is used for the production of the therapeutic radioisotope Sm-145. Sm-147 has been bombarded with Ca-40 to produce the short-lived radioisotopes Pb-182. Sm-148 has been used to study the giant monopole resonance while Sm-149 has been used in a filter for polarizing thermal neutrons. Sm-152 is used for the production of the radioisotope Sm-153 which is used for bone pain palliation. Finally, Sm-154 has been used to study the excited states of Sm-153.
| Isotope | Mass /Da |
Natural abund. (atom %) |
Nuclear spin (I) |
Nuclear magnetic moment (μ/μN) |
|---|---|---|---|---|
| 144Sm | 143.911998 (4) | 3.07 (7) | 0 | |
| 147Sm | 146.914894 (4) | 14.99 (18) | 7/2 | -0.8149 |
| 148Sm | 147.914819 (4) | 11.24 (10) | 0 | |
| 149Sm | 148.917180 (4) | 13.82 (7) | 7/2 | -0.6718 |
| 150Sm | 149.917273 (4) | 7.38 (1) | 0 | |
| 152Sm | 151.919728 (4) | 26.75 (16) | 0 | |
| 154Sm | 153.922205 (4) | 22.75 (29) | 0 |
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