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The Element Neptunium

[Click for Isotope Data]





Atomic Number: 93

Atomic Weight: 237

Melting Point: 917 K (644°C or 1191°F)

Boiling Point: 4175 K (3902°C or 7056°F)

Density: 20.25 grams per cubic centimeter

Phase at Room Temperature: Solid

Element Classification: Metal

Period Number: 7    Group Number: none    Group Name: Actinide

Radioactive and Artificially Produced

What's in a name? Named for the planet Neptune.

Say what? Neptunium is pronounced as nep-TOO-nee-em.

History and Uses:

Neptunium was first produced by Edwin M. McMillian and Philip H. Abelson, working at the University of California, Berkeley, in 1940. They produced neptunium-239, an isotope of neptunium with a half-life of about 2.4 days, by bombarding uranium with slow moving neutrons.

Neptunium's most stable isotope, neptunium-237, has a half-life of about 2,144,000 years. It decays into protactinium-233 through alpha decay. Neptunium-237, which is produced in gram quantities as a by-product of the production of plutonium in nuclear reactors, is used in neutron detectors.

Once considered to be completely artificial, extremely small amounts of neptunium are produced naturally in uranium ores through the interaction of atoms of uranium in the ore with neutrons produced by the decay of other atoms of uranium in the ore.

Estimated Crustal Abundance: Not Applicable

Estimated Oceanic Abundance: Not Applicable

Number of Stable Isotopes: 0   (View all isotope data)

Ionization Energy: 6.266 eV

Oxidation States: +6, +5, +4, +3

Electron Shell Configuration:


2s2   2p6

3s2   3p6   3d10

4s2   4p6   4d10   4f14

5s2   5p6   5d10   5f4

6s2   6p6   6d1