93
Np
237
Neptunium (Np)
Element 93 · Period 7 · Actinide series
actinide
solid at room temp
f-block
radioactive
synthetic
About Neptunium
First transuranic element. Created in nuclear reactors as byproduct of uranium irradiation.
Physical Properties
Atomic Mass
237 u
State at 25°C
Solid
Melting Point
637 °C
Boiling Point
4000 °C
Density
20.2 g/cm³
Magnetism
Paramagnetic
Atomic Properties
Electron Configuration
[Rn] 5f⁴ 6d¹ 7s²
Electron Shells
2, 8, 18, 32, 22, 9, 2
Electronegativity
1.36
Atomic Radius
221 pm
Ionization Energy
605 kJ/mol
Oxidation States
+3 to +7
Discovery & History
Discovered By
Edwin McMillan
Discovery Year
1940
Named By
Edwin McMillan
Name origin: Planet Neptune
Frequently Asked Questions
- Is Neptunium a metal, nonmetal, or metalloid?
- Neptunium is classified as a actinide.
- What state is Neptunium in at room temperature?
- Neptunium is a solid at standard room temperature (25°C).
- What is the atomic mass of Neptunium?
- Neptunium has an atomic mass of 237 atomic mass units (u).
- Who discovered Neptunium?
- Neptunium was discovered by Edwin McMillan in 1940.
- Where is Neptunium on the periodic table?
- Neptunium is element number 93, located in period 7, part of the actinide series shown below the main table.