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Neptunium

Document v1 · published by Koskamo · updated 2026-10-04

Original source

Neptunium (Np) is chemical element 93, an actinide in the f-block, period 7 (PubChem).

  • Atomic number: 93
  • Symbol: Np
  • Group: none (f-block)
  • Period: 7
  • Atomic mass: 237.048172 u
  • Electron configuration: [Rn]7s2 5f4 6d1
  • Electronegativity (Pauling scale): 1.36
  • Atomic radius (van der Waals): 221 pm
  • Ionization energy: 6.266 eV
  • Oxidation states: +6, +5, +4, +3
  • Standard state: Solid
  • Melting point: 917 K
  • Boiling point: 4175 K
  • Density: 20.25 g/cm³
  • Chemical group: Actinide
  • Year discovered: 1940

Source and provenance

Original source
pubchem.ncbi.nlm.nih.gov
Published on Koskamo by
Koskamo
Citation version
Document v1
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PubChem periodic table data (NIH/NLM, pubchem.ncbi.nlm.nih.gov/ptable); group and period from Jefferson Lab via PubChem

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Version history

  1. Published by Koskamo

    Version 1