093Actinide · Group 3 · Period 7
Neptunium
Neptunium (Np) is element 93, a actinide in the f-block — group 3, period 7. It is a solid at room temperature with 7 electron shells (2, 8, 18, 32, 22, 9, 2) and an atomic mass of 237 u.
- Atomic mass
- 237.0 u
- Phase · STP
- solid
- Melting
- 912 K · 639 °C
- Boiling
- 4447 K · 4174 °C
- Electronegativity
- 1.36
- Density
- 20.45 g/cm³
Photograph — Los Alamos National Laboratory,, Public domain, via Wikimedia Commons
Identity
- Atomic number
- 93
- Standard atomic weight
- 237.0 u
- Category
- Actinide
- Group
- 3
- Period
- 7
- Block
- f-block
- Oxidation states
- +6, +5, +4, +3
Physical properties
- Melting point
- 912 K · 639 °C
- Boiling point
- 4447 K · 4174 °C
- Density
- 20.45 g/cm³
- Molar heat capacity
- 29.46 J/(mol·K)
- Atomic radius
- 221 pm
- Electron affinity
- 45.85 kJ/mol
Atomic structure
93protons
144neutrons
93electrons
2valence e⁻
- Noble-gas notation
- [Rn] 5f4 6d1 7s2
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f4 6d1
- Electrons per shell
- 2, 8, 18, 32, 22, 9, 2
Periodic trends
Where Neptunium ranks across all 118 elements.
Discovery
- Discovered
- 1940
- Discovered by
- Edwin McMillan
- Named by
- —
- Appearance
- silvery metallic