Samarium (Sm)

Samarium is a lanthanide with atomic number 62, in period 6, in the f-block of the periodic table. Its atomic mass is 150.36 u and its electron configuration is [Xe] 4f⁶ 6s². Solid at 25 °C.

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Key facts

Atomic number	62
Atomic mass	150.36 u
Category	Lanthanide
Period	6
Group	f-block, no group number
Block	f
Electron configuration	[Xe] 4f⁶ 6s²
Electrons per shell	2, 8, 18, 24, 8, 2
Electronegativity (Pauling)	1.17
Oxidation states	+2, +3common in bold
State at 25 °C	Solid
Melting point	1345 K1071.85 °C
Boiling point	2067 K1793.85 °C
Density	7.52 g/cm³

Atomic properties

First ionization energy	5.644 eV
Electron affinity	50 kJ/mol
Atomic radius	181 pm
Covalent radius	198 pm
Van der Waals radius	229 pm
Common ions	Sm³⁺, Sm²⁺
Protons, neutrons, electrons	62, 88, 62

Physical and thermal properties

Molar volume	19.98 cm³/mol
Heat of fusion	8.5 kJ/mol
Heat of vaporization	175 kJ/mol
Specific heat	196 J/(kg·K)
Thermal conductivity	13 W/(m·K)
Thermal expansion	1.27 × 10⁻⁵ K⁻¹
Mohs hardness	1.44
Young’s modulus	50 GPa
Crystal structure	Simple trigonal
Magnetic type	Paramagnetic

Identification and history

CAS number	7440-19-9
Latin name	Samarium
Discovered by	Lecoq de Boisbaudran · 1879
Named by	---

Natural isotopes

Isotope	Mass (u)	Abundance
¹⁴⁴Sm	143.912006	3.08 %
¹⁴⁷Sm	146.914904	15 %
¹⁴⁸Sm	147.914829	11.25 %
¹⁴⁹Sm	148.917191	13.82 %
¹⁵⁰Sm	149.917282	7.37 %
¹⁵²Sm	151.919739	26.74 %
¹⁵⁴Sm	153.922216	22.74 %

Data checked against PubChem (NIH), IUPAC, the NIST Atomic Spectra Database and the IAEA (NUBASE and AME), the same data you see in the app.

A dash (---) means there is no reliable published measurement. The app never makes one up.

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Orbital diagram with Hund’s rule, emission spectrum, shell model, every isotope, a real photo, and comparison with any other element. Free, no ads, works offline.

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