Neptunium, element 93, was first produced in 1940 at the University of California, Berkeley by physicists Edwin McMillan and Philip H. Abelson. The element is named for the planet Neptune, following the pattern set by uranium. McMillan is generally credited with coining the name, although it was not used in the paper announcing the discovery. The first known use of the name is from the 30 August 1941 Science News Letter:

The uranium outpost was passed some years ago by Prof. Enrico Fermi [...] with his discovery of the radioactive element No. 93, now called neptunium.1

(In 1934, Fermi had thought he had produced element 93, but was mistaken. This 1941 article erroneously gives him credit.)

The chemical symbol for neptunium is Np.

1Oxford English Dictionary, neptunium, 3rd Edition, December 2008, Oxford University Press, accessed 19 November 2009,

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