Samarium combines with cobalt to produce strong magnets that remain useful at high temperatures. It also occurs in optical materials and can absorb neutrons in nuclear applications. These roles connect the behavior of electrons in a material to a separate interaction involving atomic nuclei.
FROM ELEMENT TO APPLICATION
AN ELEMENT IN CONTEXT
Why does a samarium–cobalt magnet need a stated operating temperature?
Samarium–cobalt permanent-magnet alloy
FOLLOW THIS RELATIONSHIP
Prepare the magnetic alloy
Samarium and cobalt form permanent-magnet materials with selected compositions. Their useful behavior belongs to the prepared alloy rather than elemental samarium alone.
Explore the model (optional)
SmFORM → INTERACTION → CONSEQUENCE
Follow the explanation in either direction. These are authored steps, not a physical clock.
Optional: check your understanding
USE THE EXPLANATION
Which test best informs selection for an elevated-temperature system?
Atomic identity, reference properties and structure models
INTERACTIVE 3D62 visible sites
An electron censusDrag to rotate · scroll or pinch to zoom
[Xe] 4f6 6s2. Grouping electrons by principal shell connects the neutral-atom configuration to periodic-table patterns.
What this representation means
A three-dimensional counting diagram. Dots are count markers, not measured electron positions; spherical placement and spacing are arbitrary. There are no electron trajectories here. Orbitals describe quantum states.
Paul-Émile Lecoq de Boisbaudran identified samarium in 1879 while investigating material derived from the samarskite. Differences during and a distinctive revealed another rare-earth constituent. Samarium preparations were themselves later found to contain other elements, including europium, separated in 1901. The repeated pattern explains a major nineteenth-century challenge: a successful separation could improve purity substantially without yet producing a truly single-element sample.
1879
Samarium identified
Lecoq de Boisbaudran distinguished samarium using chemical separation and spectroscopy.
1901
Another constituent separated
Demarçay obtained europium from samarium-containing material.
Samarium occurs in rare-earth minerals including monazite and bastnaesite. It shares these resources with elements that have similar chemical behavior. A mineral concentrate therefore needs further separation before it becomes a samarium product. The eventual form depends on whether the destination is a magnetic or another specialized material.
Samarium's roles include permanent-magnet alloys and neutron-absorbing materials. These uses arise from different interactions: magnetism concerns the material's electronic structure, while capture involves . A samarium–cobalt magnet should therefore not be explained as radioactive, nor should a neutron absorber be treated as merely a very strong magnet.
Each section links its supporting references. Descriptions and diagrams were authored for this atlas. Source checks completed. Source checks dated 2026-09-06.
CITE THIS PAGE
Family labels and the group-3 layout are teaching conventions. A table position does not establish an unknown bulk property. Electronic configurations refer to neutral atoms; ions and material environments require their own account.
Read each reference property together with its units, conditions and the reference information below.
Not yet recorded: electron affinity, second ionization energy, ground-state term symbol, van der waals radius, thermal conductivity, specific heat capacity, electrical resistivity, crystal structure, lattice parameter a, space group, abundance in seawater, abundance in the universe, annual production, supply-risk listing, hazard classification, biological role, cas registry number, pubchem cid, wikidata item. These families are declared and awaiting an ingestion run against the source each names; they are listed here rather than shown as empty rows.
Physical
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Phase at 20 °C
solid
293.15 K, 101.325 kPa
Melting point in K
1345 K
at standard pressure unless noted
Boiling point in K
2067 K
101.325 kPa
Density in g/cm³
7.52 g/cm³
solids and liquids at 293 K; gases at 273 K and 101.325 kPa
Atomic and electronic
Intended reference: Pauling electronegativity scale · Widely tabulated; original in The Nature of the Chemical Bond
Electronegativity in Pauling
1.17 Pauling
Pauling scale
First ionization energy in kJ/mol
544.5 kJ/mol
gas-phase neutral atom, ground state
Covalent radius in pm
198 pm
single-bond covalent radius
Common oxidation states
+2, +3
states met in ordinary compounds; not exhaustive
Occurrence and identity
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Abundance in the crust in mg/kg
7.05 mg/kg
upper continental crust, mass fraction
Has stable isotopes
Yesderived
Discovery year in CE
1879 CEderived
WHERE IT SITS AMONG ITS NEIGHBORS
Electronegativity across period 6
Sm 1.17 Pauling · Samarium
Electronegativity across period 6. Exact values.
Cs
0.79
Ba
0.89
La
1.1
Ce
1.12
Pr
1.13
Nd
1.14
Sm
1.17
Eu
1.2
Gd
1.2
Tb
1.1
Dy
1.22
Ho
1.23
Er
1.24
Tm
1.25
Yb
1.1
Lu
1.27
Hf
1.3
Ta
1.5
W
2.36
Re
1.9
Os
2.2
Ir
2.2
Pt
2.28
Au
2.54
Hg
2
Tl
1.62
Pb
2.33
Bi
2.02
Po
2
At
2.2
The trend uses the same reference-property values as the periodic table. Elements with no recorded value are left out of the line rather than drawn at zero.
