neptunium

nep·tu·ni·um  (np-tn-m, -ty-)

n. Symbol Np

A silvery, metallic, naturally radioactive element, atomic number 93, the first of the transuranium elements. Its longest-lived isotope is Np-237 with a half-life of 2.1 million years. Found in trace quantities in uranium ores, it is produced synthetically by nuclear reactions. See Table at element.

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[After the planet Neptune (from the fact that it follows uranium in the periodic table).]

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neptunium

Noun

Chem a silvery metallic element synthesized in the production of plutonium Symbol: Np[after Neptune, the planet]

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neptunium  (np-tn-m)

Symbol Np

A silvery, radioactive metallic element of the actinide series. It occurs naturally in minute amounts in uranium ores and is produced artificially as a byproduct of plutonium production. Its longest-lived isotope is Np 237 with a half-life of 2.1 million years. Atomic number 93. See Periodic Table.

Thesaurus

Noun

1.

neptunium - a radioactive transuranic metallic element; found in trace amounts in uranium ores; a by-product of the production of plutonium atomic number 93, Np metal, metallic element - any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.