#62 / 118
62Sm150.36
Lanthanides (Rare Earths)solid at STPF-block

Samarium

Group: f-blockPeriod: 6Standard Atomic Weight: 150.36 u

Why is Samarium in this position?

Understanding the scientific rationale behind Samarium's position in the periodic table:

Group Assignment
Group Lanthanide / Actinide

Lanthanide series element filling the 4f subshell.

Period Assignment
Period 6

Belongs to Period 6 because its outermost electrons occupy n=6.

Orbital Block
F-block

Belongs to the f-block because differentiating electrons enter 4f orbitals (4f⁶ 6s²).

Chemical Category
Lanthanides (Rare Earths)

Classified as a lanthanide rare earth metal with prominent magnetic and nuclear properties.

Atomic Structure & Bohr Shell Model

Shell Distribution: [2, 8, 18, 24, 8, 2]

Bohr Atomic Shell Model(2, 8, 18, 24, 8, 2)

Hover or tap any shell orbit ring to inspect electron counts and 2n² capacities.

62 Protons (p⁺)88 Neutrons (n⁰)
KShell K: Electron 1 of 2Shell K: Electron 2 of 2LShell L: Electron 1 of 8Shell L: Electron 2 of 8Shell L: Electron 3 of 8Shell L: Electron 4 of 8Shell L: Electron 5 of 8Shell L: Electron 6 of 8Shell L: Electron 7 of 8Shell L: Electron 8 of 8MShell M: Electron 1 of 18Shell M: Electron 2 of 18Shell M: Electron 3 of 18Shell M: Electron 4 of 18Shell M: Electron 5 of 18Shell M: Electron 6 of 18Shell M: Electron 7 of 18Shell M: Electron 8 of 18Shell M: Electron 9 of 18Shell M: Electron 10 of 18Shell M: Electron 11 of 18Shell M: Electron 12 of 18Shell M: Electron 13 of 18Shell M: Electron 14 of 18Shell M: Electron 15 of 18Shell M: Electron 16 of 18Shell M: Electron 17 of 18Shell M: Electron 18 of 18NShell N: Electron 1 of 24Shell N: Electron 2 of 24Shell N: Electron 3 of 24Shell N: Electron 4 of 24Shell N: Electron 5 of 24Shell N: Electron 6 of 24Shell N: Electron 7 of 24Shell N: Electron 8 of 24Shell N: Electron 9 of 24Shell N: Electron 10 of 24Shell N: Electron 11 of 24Shell N: Electron 12 of 24Shell N: Electron 13 of 24Shell N: Electron 14 of 24Shell N: Electron 15 of 24Shell N: Electron 16 of 24Shell N: Electron 17 of 24Shell N: Electron 18 of 24Shell N: Electron 19 of 24Shell N: Electron 20 of 24Shell N: Electron 21 of 24Shell N: Electron 22 of 24Shell N: Electron 23 of 24Shell N: Electron 24 of 24OShell O: Electron 1 of 8Shell O: Electron 2 of 8Shell O: Electron 3 of 8Shell O: Electron 4 of 8Shell O: Electron 5 of 8Shell O: Electron 6 of 8Shell O: Electron 7 of 8Shell O: Electron 8 of 8PShell P: Electron 1 of 2Shell P: Electron 2 of 2SmZ = 62

Educational Note: This Niels Bohr planetary model visually illustrates principal quantum energy shells ($n=1, 2, 3\dots$) and electron counts. In modern quantum mechanics (Schrödinger model), electrons do not orbit in fixed circular planetary tracks, but exist as 3D probability clouds (orbitals: $s, p, d, f$) governed by the Heisenberg uncertainty principle.

Electron Shell Filling Breakdown

Shell K (n=1):2 / 2 electrons (100%)
Shell L (n=2):8 / 8 electrons (100%)
Shell M (n=3):18 / 18 electrons (100%)
Shell N (n=4):24 / 32 electrons (75%)
Shell O (n=5):8 / 50 electrons (16%)
Shell P (n=6):2 / 72 electrons (3%)
Aufbau Electron Configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f⁶ 5s² 5p⁶ 6s²

Neutral ground state configuration. Valence electrons: 8.

Atomic & Quantum Properties

Electronegativity (Pauling)1.17 Pauling
1st Ionization Energy544.5 kJ/mol
Electron Affinity-50 kJ/mol
Atomic Radius (empirical)185 pm
Common Oxidation States+3, +2
Crystal StructureRhombohedral (Sm-type)

Physical & Thermal Properties

Density at STP7.52 g/cm³
Melting Point1072 °C (1345 K)
Boiling Point1794 °C (2067 K)
Magnetic OrderingParamagnetic
Discovery Year1879
Discovered ByPaul-Émile Lecoq de Boisbaudran

Real-World Uses, Occurrence & Compounds

Major Industrial & Everyday Uses
  • Samarium-Cobalt (SmCo) high-temperature permanent magnets in military aircraft actuators and electric guitar pickups
  • Samarium-153 (Quadramet) targeted radiopharmaceutical bone cancer pain palliation
  • Control rods in nuclear submarine reactors (Samarium-149 is a voracious neutron poison)
  • Organic synthesis reducing agent (Kagan's reagent / SmI₂)
Occurrence in Nature

Extracted from monazite, bastnäsite, and samarskite mineral ores.

Etymology & Name Origin

Named after the mineral samarskite, itself named after Russian mining engineer Vasili Samarsky-Bykhovets

Important Chemical Compounds
SmCo₅ (Samarium-cobalt magnet)
Sm₂O₃ (Samarium oxide)
SmI₂ (Samarium diiodide / Kagan's reagent)
Interesting Chemical Facts
  • Samarium was the very first chemical element in history to be named after a real living person (Russian mining official Vasili Samarsky-Bykhovets).
  • Samarium diiodide (SmI₂) is a deep blue single-electron reducing agent celebrated across organic synthesis.
  • SmCo magnets are chosen over NdFeB magnets for stealth fighters and aerospace missiles because they will not demagnetize when overheated.
Safety & Handling Note

Low biological toxicity; samarium metal dust is a flammable ignition hazard.