neptunium

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Symbol:

Np

Atomic Number:

93

Relative Atomic Mass:

237.0482 g mol^-1

Natural Abundance in Lithosphere, hydrosphere and atmosphere:

4 x 10^-17% (mass fraction)

Electron Configuration:

[Rn]5f⁴6d7s²

Oxidation States:

VI, V, IV, III

Atomic Radius:

130pm

Ionic Radius:

72pm (for +6 oxidation state)

75pm (for +5 oxidation state)

101pm (for +3 oxidation state)

Melting Point:

640°C

Density:

20.48 g cm^-3 (at 20°C)

Reduction Potential:

-1.856V

for Np³⁺ + 3e^- a Np_(s)

Electronegativity (Allred and Rochow):

1.2