Element: Neptunium (Np)

Element (Atom) NameNeptunium
Physical state at room temperatureSolid
Element ClassificationMetal
Group NameActinide
Period Number (Periodic table) 7
Group number (Periodic table)None
Atomic number93
Atomic weight237 (Ref: Jlab-ele093, Lanl-93, Nist-93)
Atomic Radius221 pm (Van der Waals) (Ref: Lanl-93)
Density20.25 g/cm3 (Ref: Jlab-ele093)
Melting point644°C (Ref: Jlab-ele093, Lanl-93)
Boiling point3902°C (Ref: Jlab-ele093)
4174 °C (Ref: Lanl-93)
Electron shell configuration1s2 
2s2 2p6 
3s2 3p6 3d10 
4s2 4p6 4d10 4f14 
5s2 5p6 5d10 5f4
6s2 6p6 6d1
Oxidation States+6, +5, +4, +3 (Ref: Jlab-ele093)
7, 6, 5, 4, 3, 2 (Ref: Lanl-93)
Ionization Energy6.266 eV (Ref: Jlab-ele093)
6.26554  eV (Ref: Nist-93)
Number of Stable Isotopes0
RemarksRadioactive, Artificially Produced


  • Jlab-ele093: https://education.jlab.org/itselemental/ele093.html
  • Lanl-93: https://periodic.lanl.gov/93.shtml
  • ciaaw-atomic-weights: https://www.ciaaw.org/atomic-weights.htm
  • Nist-93: https://physics.nist.gov/cgi-bin/Elements/elInfo.pl?element=93
  • Pubchem-93: https://pubchem.ncbi.nlm.nih.gov/element/93
  • science.co.il: https://www.science.co.il/elements/

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