Samarium (Sm)
lanthanideSolid
Standard Atomic Weight
150.36 uElectron configuration
[Xe] 6s2 4f6Melting point
1073.85 °C (1347 K)Boiling point
1793.85 °C (2067 K)Density
7520 kg/m³Oxidation states
0, +1, +2, +3Electronegativity (Pauling)
1.17Ionization energy (1st)
Discovery year
1878Atomic radius
185 pmDetails
Samarium is a lanthanide metal with atomic number 62. It is a typical rare-earth element in its trivalent chemistry, but it is also notable for accessible divalent compounds and for the strong neutron-absorbing isotope ¹⁴⁹Sm. The element occurs with other light rare earths in minerals such as monazite and bastnäsite. Its technological importance is concentrated in permanent magnets, neutron control, phosphors, and specialized chemical reducing agents.
Samarium has a bright silver luster and is reasonably stable in air. Three crystal modifications of the metal exist, with transformations at 734 and 922°C. The metal ignites in air at about 150°C. The sulfide has excellent high-temperature stability and good thermoelectric efficiencies up to 1100°C.
The name derives from the mineral samarskite, in which it was found and that had been named for Colonel Samarski, a Russian mine official. Samarium was originally discovered in 1878 by the Swiss chemist Marc Delafontaine, who called it decipium. It was also discovered by the French chemist Paul-Emile Lecoq de Boisbaudran in 1879. In 1881, Delafontaine determined that his decipium could be resolved into two elements, one of which was identical to Boisbaudran's samarium. In 1901, the French chemist Eugène-Anatole Demarçay showed that this samarium earth also contained europium.
Samarium was observed spectroscopically by Jean Charles Galissard de Marignac, a Swiss chemist, in a material known as dydimia in 1853. Paul-Émile Lecoq de Boisbaudran, a French chemist, was the first to isolate samarium from the mineral samarskite ((Y, Ce, U, Fe)3(Nb, Ta, Ti)5O16) in 1879. Today, samarium is primarily obtained through an ion exchange process from monazite sand ((Ce, La, Th, Nd, Y)PO4), a material rich in rare earth elements that can contain as much as 2.8% samarium.
Discovered spectroscopically by its sharp absorption lines in 1879 by Lecoq de Boisbaudran in the mineral samarskite, named in honor of a Russian mine official, Col. Samarski.
Images
Properties
Physical
Chemical
Thermodynamic
Nuclear
Abundance
Reactivity
N/A
Crystal Structure
Electronic Structure
Identifiers
Electron Configuration Measured
Sm: 4f⁶ 6s²[Xe] 4f⁶ 6s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f⁶ 6s²Atomic model
Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.
Schematic atomic model, not to scale.
Atomic Fingerprint
Emission / Absorption Spectrum
Isotope Distribution
| Mass number | Atomic mass (u) | Natural abundance | Half-life |
|---|---|---|---|
| 144 Stable | 143.9120065 ± 0.0000021 | 3.0700% | Stable |
| 150 Stable | 149.9172829 ± 0.0000018 | 7.3800% | Stable |
| 152 Stable | 151.9197397 ± 0.0000018 | 26.7500% | Stable |
Phase / State
Reason: 1048.8 °C below melting point (1073.85 °C)
Schematic, not to scale
Phase transition points
Transition energies
Energy required to melt 1 mol at melting point
Energy required to vaporize 1 mol at boiling point
Energy required to sublime 1 mol at sublimation point
Density
At standard conditions
At standard conditions
Atomic Spectra
Showing 10 of 62 Atomic Spectra. Sorted by ion charge (ascending).
Lines Holdings ?
| Ion | Charge | Total lines | Transition probabilities | Level designations |
|---|---|---|---|---|
| Sm I | 0 | 162 | 7 | 11 |
| Sm II | +1 | 635 | 7 | 14 |
Levels Holdings ?
| Ion | Charge | Levels |
|---|---|---|
| Sm I | 0 | 501 |
| Sm II | +1 | 377 |
| Sm III | +2 | 58 |
| Sm IV | +3 | 24 |
| Sm V | +4 | 2 |
| Sm VI | +5 | 2 |
| Sm VII | +6 | 2 |
| Sm VIII | +7 | 2 |
| Sm IX | +8 | 2 |
| Sm X | +9 | 2 |
Crystal structure data not available
Crystal structure: rhombohedral
Ionic Radii
| Charge | Coordination | Spin | Radius |
|---|---|---|---|
| +2 | 7 | N/A | 122 pm |
| +2 | 8 | N/A | 127 pm |
| +2 | 9 | N/A | 132 pm |
| +3 | 6 | N/A | 95.8 pm |
| +3 | 7 | N/A | 102 pm |
| +3 | 8 | N/A | 107.89999999999999 pm |
| +3 | 9 | N/A | 113.19999999999999 pm |
| +3 | 12 | N/A | 124 pm |
Compounds
Isotopes (3)
Twenty one isotopes of samarium exist. Natural samarium is a mixture of several isotopes, three of which are unstable with long half-lives.
| Mass number | Atomic mass (u) | Natural abundance | Half-life | Decay mode | |
|---|---|---|---|---|---|
| 144 Stable | 143.9120065 ± 0.0000021 | 3.0700% ± 0.0700% | Stable | stable | |
| 150 Stable | 149.9172829 ± 0.0000018 | 7.3800% ± 0.0100% | Stable | stable | |
| 152 Stable | 151.9197397 ± 0.0000018 | 26.7500% ± 0.1600% | Stable | stable |
Extended Properties
Covalent Radii (Extended)
Van der Waals Radii
Atomic & Metallic Radii
Numbering Scales
Electronegativity Scales
Polarizability & Dispersion
Miedema Parameters
Supply Risk & Economics
Phase Transitions & Allotropes
| Melting point | 1345.15 K |
| Boiling point | 2067.15 K |
Oxidation State Categories
Advanced Reference Data
Screening Constants (13)
| n | Orbital | σ |
|---|---|---|
| 1 | s | 1.2217 |
| 2 | p | 4.269 |
| 2 | s | 16.2652 |
| 3 | d | 13.7711 |
| 3 | p | 19.5815 |
| 3 | s | 19.9736 |
| 4 | d | 33.7604 |
| 4 | f | 38.4684 |
| 4 | p | 30.912 |
| 4 | s | 29.7076 |
Crystal Radii Detail (8)
| Charge | CN | Spin | rcrystal (pm) | Origin |
|---|---|---|---|---|
| 2 | VII | 136 | ||
| 2 | VIII | 141 | ||
| 2 | IX | 146 | ||
| 3 | VI | 109.8 | from r^3 vs V plots, | |
| 3 | VII | 116 | estimated, | |
| 3 | VIII | 121.9 | from r^3 vs V plots, | |
| 3 | IX | 127.2 | from r^3 vs V plots, | |
| 3 | XII | 138 | calculated, |
Isotope Decay Modes (52)
| Isotope | Mode | Intensity |
|---|---|---|
| 128 | B+ | — |
| 128 | B+p | — |
| 129 | B+ | 100% |
| 129 | B+p | — |
| 130 | B+ | — |
| 131 | B+ | 100% |
| 131 | B+p | — |
| 132 | B+ | 100% |
| 132 | B+p | — |
| 133 | B+ | 100% |
X‑ray Scattering Factors (508)
| Energy (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 0.18764 |
| 10.1617 | — | 0.19534 |
| 10.3261 | — | 0.20334 |
| 10.4931 | — | 0.21168 |
| 10.6628 | — | 0.22036 |
| 10.8353 | — | 0.22939 |
| 11.0106 | — | 0.2388 |
| 11.1886 | — | 0.24859 |
| 11.3696 | — | 0.25878 |
| 11.5535 | — | 0.26939 |
Additional Data
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
7.05 milligrams per kilogram
References (1)
- [5] Samarium https://education.jlab.org/itselemental/ele062.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
4.5×10-7 milligrams per liter
References (1)
- [5] Samarium https://education.jlab.org/itselemental/ele062.html
Sources
Sources of this element.
Samarium is found along with other members of the rare-earth elements in many minerals, including monazite and bastnasite, which are commercial sources. It occurs in monazite to the extent of 2.8%. While misch metal containing about 1% of samarium metal, has long been used, samarium has not been isolated in relatively pure form until recently. Ion-exchange and solvent extraction techniques have recently simplified separation of the rare earths from one another; more recently, electrochemical deposition, using an electrolytic solution of lithium citrate and a mercury electrode, is said to be a simple, fast, and highly specific way to separate the rare earths. Samarium metal can be produced by reducing the oxide with lanthanum.
References (1)
- [6] Samarium https://periodic.lanl.gov/62.shtml
References
(9)
Data deposited in or computed by PubChem
The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.
Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.
The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.
Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/
The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.
The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database
This section provides all form of data related to element Samarium.
The element property data was retrieved from publications.