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.
- ‘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.’
- ‘When struck by neutrons, nuclei of neptunium and other nuclear materials can fission into two smaller nuclei.’
- ‘The new elements were named neptunium and plutonium, respectively.’
- ‘They had to be named after the next two planets, and so were called neptunium and plutonium - both found at Berkeley using the new cyclotron.’
- ‘The Berkeley cyclotron created many elements never found in nature - including plutonium, which directly follows neptunium in the table.’
- ‘All isotopes of neptunium are radioactive, the longest lived being neptunium - 237 with a half life of 2,140,000 years.’
- ‘They produced neptunium, which decayed by beta emission, shunting the element one place further along the Periodic Table.’
- ‘As beta decay does not change the atomic mass, the isotope of the new element number 93, neptunium, also has mass 239.’
Late 19th century from Neptune, on the pattern of uranium (Neptune being the next planet beyond Uranus).