Element 93
Neptunium (Np)
Neptunium (Np) is element 93 of the periodic table, a actinide in period 7 (f-block) with an atomic mass of 237 and is a solid at standard conditions.
At a glance
- Atomic number
- 93
- Symbol
- Np
- Atomic mass
- 237 u
- Category
- Actinides
- Period
- 7
- Block
- f-block
- Phase at STP
- solid
Electron structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 5f4 6d1 7s2
- Shorthand configuration
- [Rn] 5f4 6d1 7s2
- Electrons per shell
- 2, 8, 18, 32, 22, 9, 2
- Oxidation states
- +2, +3, +4, +5, +6, +7
Physical properties
- Melting point
- 917 K
- Boiling point
- 4273 K
- Density
- 20.45 g/cm3
- Phase
- solid
Atomic properties
- Electronegativity (Pauling)
- 1.36
- Atomic radius
- 155 pm
- Covalent radius
- 190 pm
- First ionization energy
- 605 kJ/mol
- Electron affinity
- 46 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| Np-237 | 237.04817 | — | Half-life 2.14 million years |
Common uses
- Neutron detection
- Weapons research
- Spacecraft power
Discovery
- Year
- 1940
- Discovered by
- Edwin McMillan, Philip Abelson
- Country
- USA