NO. 093Actinide

Np

Neptunium

Neptunium was the first transuranium element discovered. It is radioactive and mainly produced in nuclear reactors for research and weapons-related studies.

Crystal Structure

Orthorhombic

Technical Specifications

Atomic Mass237 u

Density20.5 g/cm³

Melting Point917 K

Boiling Point4273 K

Atomic Radius155 pm

Electronegativity1.36

Ionization Energy604 kJ/mol

Electron Affinity45 kJ/mol

Bonding TypeMetallic

Oxidation States3, 4, 5, 6, 7

Acid/BaseBasic

ReactivityHigh

Electron Configuration

[Rn] 5f4 6d1 7s2

Discovered ByEdwin McMillan

Year1940

Known Isotopes

Np-237