062Lanthanide · Group 3 · Period 6

Samarium

Samarium (Sm) is element 62, a lanthanide in the f-block — group 3, period 6. It is a solid at room temperature with 6 electron shells (2, 8, 18, 24, 8, 2) and an atomic mass of 150.362 u.

Atomic mass: 150.4 u
Phase · STP: solid
Melting: 1345 K · 1072 °C
Boiling: 2173 K · 1900 °C
Electronegativity: 1.17
Density: 7.52 g/cm³

Photograph — Unknown authorUnknown author, CC BY 1.0 <https://creativecommons.org/licenses/by/1.0>, via Wikimedia Commons, source: https://images-of-elements.com/samarium.php

Identity

Atomic number: 62
Standard atomic weight: 150.4 u
Category: Lanthanide
Group: 3
Period: 6
Block: f-block
Oxidation states: +3, +2

Physical properties

Melting point: 1345 K · 1072 °C
Boiling point: 2173 K · 1900 °C
Density: 7.52 g/cm³
Molar heat capacity: 29.54 J/(mol·K)
Atomic radius: 229 pm
Electron affinity: 15.63 kJ/mol

Atomic structure

62protons

88neutrons

62electrons

2valence e⁻

Noble-gas notation: [Xe] 4f6 6s2
Full configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f6
Electrons per shell: 2, 8, 18, 24, 8, 2

Periodic trends

Where Samarium ranks across all 118 elements.

Electronegativity1.17

Ionization energy544.5 kJ/mol

Electron affinity15.63 kJ/mol

Density7.52 g/cm³

Atomic radius229 pm

Ionization energies

Energy to remove each successive electron (kJ/mol).

544.5

1.1k

2.3k

4.0k

Successive ionization energies (kJ/mol, log scale).

Discovery

Discovered: 1879
Discovered by: Lecoq de Boisbaudran
Named by: —
Appearance: silvery white