Name: neptunium
Symbol: Np
Atomic number: 93
Atomic weight: [ 237 ]
Group in periodic table:
Group name: Actinoid
Period in periodic table: 7 (actinoid)
Block in periodic table: f-block
CAS registry ID: 7439-99-8
Neptunium is a radioactive rare earth metal and has at least 3 allotropic forms. It is named for the planet Neptune. Np-237 is a by-product from nuclear reactors.