93Np237.000
Actinidef-blockRadioactive
Neptunium
Element 93 on the periodic table, symbol Np, group 3, period 7.
Neptunium is a chemical element with symbol Np and atomic number 93. A radioactive actinide metal, neptunium is the first transuranic element. Its position in the periodic table just after uranium, named after the planet Uranus, led to it being named after Neptune, the next planet beyond Uranus.
Appearance: silvery metallic
Properties
- Atomic Number
- 93
- Atomic Mass
- 237.0000 u
- Group
- 3
- Period
- 7
- Block
- f-block
- Category
- Actinide
- State at 25 °C
- Solid
- Melting Point
- 912 K · 638.9 °C
- Boiling Point
- 4,447 K · 4,173.9 °C
- Density
- 20.45 g/cm³
- Atomic Radius
- 175 pm
- Electronegativity
- 1.36
- Oxidation States
- +3, +4, +5, +6
- Abundance in Crust
- Vanishingly rare
- Discovered
- 1940
- Discovered By
- Edwin McMillan
Electron Configuration
[Rn] 5f4 6d1 7s2
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f4 6d1
Ionisation Energies (kJ/mol)
- 1. 604.5
Elements near Neptunium
Elements in the same group share the number of outer electrons and behave in similar ways. Elements in the same period share a shell, so they change steadily from left to right.