93 Np
Actinide
Neptunium
First transuranium element.
Properties of Neptunium
- Atomic number (Z)
- 93
- Symbol
- Np
- Atomic mass
- 237 g/mol
- Category
- Actinide
- Group
- 3
- Period
- 7
- Electron configuration
- [Rn] 5f⁴ 6d¹ 7s²
- Electronegativity (Pauling)
- 1.36
- Atomic radius
- 175 pm
- First ionization energy
- 605 kJ/mol
- Melting point
- 917 K (643.9 °C)
- Boiling point
- 4273 K (3999.8 °C)
- Density
- 20.45 g/cm³
- Phase at 25 °C
- Solid
- Discovered
- Discovered in 1940