Neptunium

Actinide

Symbol: Np

Atomic Number: 93

Standard State: Solid

Atomic Mass: 237.0482

Electron Configuration: [Rn]7s2 5f4 6d1

Electronegativity: 1.36

Atomic Radius: 221

Ionization Energy: 6.266

Melting Point: 917

Boiling Point: 4175

Density: 20.25

Year Discovered: 1940