Neptunium (Np)
"The World Beyond, the first hero to be created beyond the natural elements, following its planetary namesake."
A memorable persona to anchor Np in your mind.
20.45
Grams per cm³
644
Celsius (°C)
221
Radius (pm)
Daily Life Link
Neptunium has no everyday connection; it�s a byproduct of nuclear reactors.
Discovery & History
Year Discovered
1940
Discovered By
Edwin McMillan & Philip H. Abelson
Origin of Name
"Neptunium was named after the planet Neptune."
Technical Properties
Atomic Mass
[237] u
Standard State
solid
Boiling Point
3902°C
Electron Configuration
[Rn] 5f46d17s2
1st Ionization Energy
6.266 eV
Electron Affinity
N/A
Oxidation States
"Neptunium is a silvery, radioactive, metallic element."
Did You Know?
It was the first transuranic element (element heavier than uranium) to be synthesized.
It was named after the planet Neptune, following the planetary naming scheme started with uranium (Uranus).
Although it is primarily produced synthetically, trace amounts of neptunium are actually found in nature in uranium ores.
It has been considered for use in devices that can detect high-energy neutrons.