Np
Neptunium
Atomic number: 93Mass: 237 uCategory: Actinide
About Neptunium
Neptunium is a radioactive actinide metal. It was the first synthetic transuranium element of the actinide series. Its symbol Np is derived from the planet Neptune, as it follows uranium in the periodic table (just as Neptune follows Uranus).
Properties
Period
7
Group
N/A
Block
F
Category
Actinide
Electronegativity
1.36 (Pauling)
Ionization Energy
604.5 kJ/mol
Melting Point
912 K (639°C)
Boiling Point
4175 K (3902°C)
Density
20.2 g/cm³
Oxidation States
+3, +4, +5, +6
Electron Configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁶ 5f⁴ 6d¹ 7s²
[Rn] 5f⁴ 6d¹ 7s²
Shell 1:2e⁻
Shell 2:8e⁻
Shell 3:18e⁻
Shell 4:32e⁻
Shell 5:22e⁻
Shell 6:9e⁻
Shell 7:2e⁻
Real-World Uses
Neutron detection equipment
Nuclear research
Production of plutonium-238 (spacecraft RTGs)
Research only
No commercial uses
Fun Fact
Neptunium was synthetically created in a lab in 1940 — it was the first element ever made that doesn't naturally occur on Earth!