neptunium

Meanings

1. 1
   noun

   the radioactive transuranic chemical element with symbol Np and atomic number 93

   The reactor produced neptunium after uranium-238 captured a neutron and underwent beta decay.

Named in 1940 from Neptune + -ium. The name continues the planetary sequence begun with uranium, named for Uranus: element 93 follows uranium in the periodic table just as Neptune follows Uranus among the planets.

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