Periodic Table


Atomic number: 62
Atomic weight: 150.36
Symbol: Sm
Group number: (lanthanide)
Electronic configuration: [Xe].4f6.6s2


Samarium has a bright silver lustre and is reasonably stable in air. It ignites in air at 150°C. It is a rare earth metal. It is found with other rare earth elements in minerals including monazite and bastanite and is used in electronics industries.

General information

Discoveror: Paul Emile Lecoq de Boisbaudran
Date discovered: 1879
Discovered at: France
Meaning of name: Named after "Samarskite" (a mineral)

Physical data

Standard state: solid at 298 K
Colour: silvery white
Density of solid at ambient temperature/kg m-3: 7353
Molar volume/cm3: 19.98

Radii /pm

Atomic: 238
Covalent (single bond):
Pauling radius for the ion [Sm]-: no data

Valence shell orbital radius maxima (Rmax)
orbital s p d f
radius216.4no datano data32.1


Both values are quoted on the Pauling scale.

Pauling: 1.17
Allred Rochow: 1.07

Crystal Structure

structure: trigonal

The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.


Temperatures (/K)

melting point: 1345
boiling point: 2076

Enthalpies /kJ mol-1

fusion: 8.9
vaporization: 178

single bond enthalpies:
Sm-F Sm-Cl Sm-Br Sm-I Sm-Sm
no data no data no data 285 no data

Ionization enthalpies /kJ mol-1

Number Enthalpy


This section gives some data for naturally occurring isotopes.
Nominal mass Accurate mass % natural abundance
144Sm143.911998 (4)3.1 (1)
147Sm146.914894 (4)15.0 (2)
148Sm147.914819 (4)11.3 (1)
149Sm148.917180 (4)13.8 (1)
150Sm149.917273 (4)7.4 (1)
152Sm151.919728 (4)26.7 (2)
154Sm153.922205 (4)22.7 (2)

Further Information

Copyright 1997 Mark Winter
Department of Chemistry at the University of Sheffield, Sheffield S3 7HF, England.

The current version of this document is at http://www.shef.ac.uk/~chem/web-elements-I/Sm.html