Periodic Table

Samarium

Lanthanide

Quick Facts about Samarium

Pm
  • solid- state of matter at room temperature
  • Stable- has at least one stable isotope
  • +3, +2- common oxidation states in compounds
  • RHL- crystal structure, atomic arrangement in solid form
Eu

Samarium (Sm) is element 62 on the periodic table. Atomic mass of Sm: 150.3600 u. Sm is in period 6. Melting point of Sm: 1345.00 K.Density of Sm: 7.52 g/cm³.

Why Samarium Matters

Samarium in everyday life and industry

In Your Home

  • High-end headphones may use SmCo magnets for heat resistance
  • Some infrared-absorbing glass (special windows) contains samarium

Industry Uses

AerospaceSmCo magnets in jet engines and satellites—they work where NdFeB fails (high temps)
MedicalSm-153 (Quadramet) treats bone cancer pain by targeting metastases
NuclearControl rods use Sm-149's huge neutron capture cross-section

In Your Body

✗ Not essential

Samarium has no known biological role. Samarium-153 treats bone cancer pain.

Safety: Low general toxicity. Radioactive Sm-153 targets bone like calcium—therapeutic for cancer, but requires careful handling.

Discovery of Samarium

Discovered by Paul Émile Lecoq de Boisbaudran in France, 1879

Name origin: Named after the mineral samarskite.

History & Events

1879
Named after the mineral samarskite
1879
Samarskite was named after Russian engineer Vasili Samarsky-Bykhovets
1879
First element named after a person
1879
Discovered by Paul Émile Lecoq de Boisbaudran in 1879

About Samarium

Silvery lanthanide with seven natural isotopes. Sm-147 is radioactive (α, t1/2 ~1.06×1011 years)—crucial for Sm-Nd geochronology. Forms SmCo5 and Sm2Co17 permanent magnets that outperform NdFeB at high temperatures. Sm-149 has an enormous neutron capture cross-section (40,000 barns), useful in reactor control. Discovered 1879 by Lecoq de Boisbaudran.

Atomic Properties of Sm

Atomic Number of Sm
62
Atomic Mass of Sm
150.3600 u
Electron Configuration
[Xe] 4f6 6s2
Electronegativity
1.17
Block
f-block
Group
Period
6

Physical Properties of Sm

Phase (STP)
solid
Melting Point of Sm
1345.00 K
Boiling Point of Sm
2173.00 K
Density of Sm
7.5200 g/cm3

Thermal Properties

Heat of Fusion
8.90 kJ/mol
Heat of Vaporization
165.00 kJ/mol
Specific Heat
0.20 J/g·K
Molar Heat Capacity
29.54 J/mol·K

Atomic Radii

Calculated
185 pm
Covalent
172 pm
Van der Waals
236 pm

Common Misconceptions

Wrong:Samarium-cobalt magnets are obsolete now that neodymium exists.
Correct:SmCo magnets dominate high-temperature applications (jet engines, turbines). NdFeB loses magnetism above ~150°C; SmCo works to 300°C+.
Wrong:Samarium was named after a scientist who discovered it.
Correct:Named after the mineral samarskite, which honored Vasili Samarsky-Bykhovets—a Russian mining engineer, not a scientist. First element named after a person.
Wrong:All samarium isotopes are stable.
Correct:Sm-147 is radioactive (α, t1/2 ~1011 years) and decays to Nd-143. This Sm-Nd system is crucial for dating ancient rocks and meteorites.

Isotopes of Samarium

Samarium has 6 naturally occurring isotopes, plus 3 notable radioactive isotopes.

IsotopeAtomic Mass (u)AbundanceHalf-LifeDecay Mode
14462Sm (Sm-144)Samarium-144 isotope143.91200653.070%
14662Sm (Sm-146)Samarium-146 isotope145.9130470%103 million yearsα
14762Sm (Sm-147)Samarium-147 isotope146.914904414.99%1.06×10¹¹ yearsα
14862Sm (Sm-148)Samarium-148 isotope147.914829211.24%
14962Sm (Sm-149)Samarium-149 isotope148.917192113.82%
15062Sm (Sm-150)Samarium-150 isotope149.91728297.380%
15262Sm (Sm-152)Samarium-152 isotope151.919739726.75%
15362Sm (Sm-153)Samarium-153 isotope152.92209740%46.3 hoursβ⁻
15462Sm (Sm-154)Samarium-154 isotope153.922216922.75%

Data source: NIH PubChem (aggregated from IUPAC, NIST)

Isotope Applications

Isotopes of Samarium have important real-world applications in science and industry.

Geochronology & Dating

147Sm is used for determining formation ages of igneous and metamorphic rocks via analysis of the minerals which compose them, such as those shown in Fig. IUPAC.62.1 [440], [441], [442].

Medical Applications

The radioisotope 153Sm (with a half-life of 1.9 days) is used in medicine to treat the severe pain associated with cancer that has spread to bones (Fig. IUPAC.62.2) [443], [444], [445].

Abundance

Earth's Crust
7.0 mg/kg
Seawater
4.50×10-7 mg/L

Uses

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.

Geochemistry

Goldschmidt
litophile
Geochemical Class
rare earth & related

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