Neptunium

Symbol: Np
Atomic number: 93
Category: actinides
Group: n/a
Period: 7
Block: f
Atomic weight: (237) g/mol
Electrons per shell: 2, 8, 18, 32, 22, 9, 2
CAS number: 7439-99-8
Phase: solid
Density: 20.45 kg/l (near room temperature)
Melting point: 910 K (637C, 1179F)
Boiling point: 4273 K (4000C, 7232F)
Crystal structure: orthorhombic, tetragonal and cubic
Oxidation states: 3, 4, 5, 6
Electronegativity: 1.36 (Pauling scale)
Name's origin: Neptunus
Name's meaning: the planet in the Solar System
Facts:
- is silvery in color
- is found in three allotropes: alpha-, beta- and gamma-neptunium
- is fissionable, and could theoretically be used as fuel in a fast neutron reactor or a nuclear weapon
- is also used in neutron detection devices
- trace amounts of neptunium are found naturally as decay products from transmutation reactions in uranium ores
- due to its long half life neptunium becomes the major contributor of the total radiation in 10000 years
- is fairly reactive chemically