CAS Number54386-24-2
PubChem CIDna
Atomic Radius-
Atomic Volume-
Atomic Weight[281]
Boiling Point-
Bulk Modulus
CategoryTransition metals
Crystal Structure
Covalent Radius121
Electrical Resistivity
Electron Configuration[Rn] 5f14 6d9 7s2
Electrons per shell2, 8, 18, 32, 32, 17, 2
Heat of Fusionna
Heat of Vaporizationna
Ionization Potential-
Magnetic Ordering
Magnetic Susceptibility
Mass Number111
Melting Point-
Atomic Number281
Oxidation States-1, 1, 3, 5
Poisson Ratio
Shear Modulus
Specific Heat Capacity-
Thermal Conductivity-
Van der Waals radius
Young's Modulus
Abundance in Earth's crustna
Abundance in Universena
Rg Roentgenium 111 (280) 11 7 d 111 [Rn] 5f14 6d10 7s1 2 8 18 32 32 17 2 None Unknown 1 10 m 14.5m AlphaEmission TransitionMetal, Metal, Radioactive, Synthetic oon-nun-OON-i-em Synthetic radioactive metal. It has no significant commercial applications. Made by bombarding bismuth-209 with nickel-60. MTq1hzhCF0g Roentgenium
Neptunium was the first synthetic transuranium element of the actinide series to be discovered.

Neptunium was first produced by Edwin McMillan and Philip H. Abelson in 1940 at Berkeley Radiation Laboratory of the University of California.

The team produced the neptunium isotope 239Np by bombarding uranium with slow moving neutrons. Named after the planet Neptune 111 1994 S. Hofmann, V. Ninov, F. P. Hessberger, P. Armbruster, H. Folger, G. Münzenberg, and others Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany. The proposed name roentgenium has yet ot be accepted formally, but lies within the long established tradition of naming elements to honour famous scientists. Wilhelm Conrad Roentgen discovered X-rays in 1895

Isotopes of Neptunium

Standard Atomic Weight

Stable Isotopes

Unstable Isotopes

272Rg 273Rg 274Rg 275Rg 276Rg 277Rg 278Rg 279Rg 280Rg 281Rg 282Rg 283Rg

Neptunium is harmful due to its radioactivity
Neptunium is obtained as a by-product from nuclear reactors
Neptunium is used mainly for research purposes.

When bombarded with neutrons 237Np is used to produce 238Pu which is used for spacecraft generators and terrestrial navigation beacons.

237Np is used in devices for detecting high-energy neutrons.