Neptunium

Actinide · 237.048172 u · group 3, period 7

Neptunium · Np

Atomic number93

SymbolNp

CategoryActinide

Standard stateSolid

Group · Period · Block3 · 7 · f

Electron configuration[Rn]7s2 5f4 6d1

Atomic mass237.048172 u

Atomic radius221 pm

Protons / Neutrons / Electrons93 / 144 / 93

Shells (e⁻ per shell)2, 8, 18, 32, 22, 9, 2

Electronegativity (Pauling)1.36

Ionization energy6.266 eV

Electron affinity—

Oxidation states+6, +5, +4, +3

Melting point917 K · 643.9 °C

Boiling point4.18e+3 K · 3.90e+3 °C

Density20.25 g/cm³

Year discovered1940

CPK color

#0080FF

State at room temp (25 °C)

solid

Position