Neptunium (Np)

Neptunium (Np)

Atomic Number: 93
Atomic Weight: 237.05
Melting Point: 640
Boiling Point: 3902
Specific Gravity: 18.0-20.45 (depending on allotropic form)
Valences: 3,4,5 and 6

Neptunium was produced in 1940 by McMillan and Abelson. Neptunium is a radioactive element that is usually made in the laboratory, but can be found naturally in minute quantities in association with Uranium ores. This was the first element higher in atomic number than Uranium to be discovered. [LM] {RW}