The chemical element of atomic number 93, a radioactive metal of the actinide series. Neptunium was discovered as a product of the bombardment of uranium with neutrons, and occurs only in trace amounts in nature. (Symbol: Np)
More example sentences
- Each tank round is 10 pounds of solid uranium - 238 contaminated with plutonium, neptunium, americium.
- In Basra they have found the bombs that were used had enriched uranium in them - neptunium.
- Just as Neptune comes right after Uranus in the solar system, so, too, does neptunium come right after uranium in the periodic table.
late 19th century: from Neptune, on the pattern of uranium (Neptune being the next planet beyond Uranus).
More definitions of neptuniumDefinition of neptunium in:
- The British & World English dictionary