neptunium

Name neptunium
Symbol Np
Atomic Weight 237.05
Atomic Number 93
CAS ID 7439-99-8
Group Number
Group Name Actinoid
Period Number 7
Origin of Name Named after the planet Neptune.
Year Discovered 1940
Discovery Credits E. M. McMillan and P. Abelson at Berkeley, California, USA.
Class Metallic
Color Silvery Metallic
Standard State Solid at 77 F & 298 K
Description Radioactive silvery metal which does not occur naturally. Attacked by oxygen, steam, and acids, but not alkalis.

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