62
Sm
Samarium
150
Samarium (Sm)
LanthanidePeriod 6f-block-block
Samarium is a chemical element with symbol Sm and atomic number 62. It is a moderately hard silvery metal that readily oxidizes in air. Being a typical member of the lanthanide series, samarium usually assumes the oxidation state +3.
Latin name: Samarium
Atomic Number
62
Atomic Mass
150 g/mol
Phase (STP)
Solid
Electron Config.
[Xe] 4f⁶ 6s²
General
SymbolSm
Atomic Number62
Atomic Mass150 g/mol
CategoryLanthanide
Period6
Blockf-block
Electron Configuration[Xe] 4f⁶ 6s²
Valence Electrons8
Coloursilvery-white metallic
Appearancesilvery white
CAS NumberCAS7440-19-9
Physical Properties
Phase (STP)Solid
Density7.52 g/cm³
Melting Point1071.85°C · 1961.33°F · 1345.00 K
Boiling Point1802.85°C · 3277.13°F · 2076.00 K
Atomic Properties
Atomic Radius229 pm
Electronegativity1.17 Pauling
Ionization Energy545 kJ/mol
Oxidation States+3, +2
Ion ChargeSm2+/Sm3+
Thermodynamic
Molar Heat29.54 J/(mol·K)
Crystal Structure
Crystal Structurerhombohedral
Mechanical Properties
Mohs Hardness2.5
Nuclear & Hazards
Half-lifestable (Sm-152 is nearly stable, t½ ≈ 7.1×10^15 years)
Abundance
In Universe0.00005%
In Sun0.00004%
In Earth's Crust0.0600%
In Meteorites0.0002%
Discovery & History
Discovery Year1879
Discovered ByPaul Émile Lecoq de Boisbaudran
Country of DiscoveryFrance
Isotopes of Samarium
| Isotope | Abundance | Half-life | Decay |
|---|---|---|---|
| Sm-144 | 3.08% | Stable | — |
| Sm-147 | 14.99% | 1.06 × 10¹¹ years | α |
| Sm-148 | 11.24% | 7 × 10¹⁵ years | α |
| Sm-149 | 13.82% | Stable | — |
| Sm-150 | 7.38% | Stable | — |
| Sm-152 | 26.75% | Stable | — |
| Sm-154 | 22.75% | Stable | — |