Definition of neptunium

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< Neptune

neral >

nep·tu·ni·um

p-t

m, -ty

-) KEY

NOUN:
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.

ETYMOLOGY:
After the planet Neptune ( from the fact that it follows uranium in the periodic table)

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