neptunium : Dictionary / Wörterbuch (BEOLINGUS, TU Chemnitz)

English Dictionary: neptunium	by the DICT Development Group
3 results for neptunium
From WordNet (r) 3.0 (2006) [wn]:
neptunium n a radioactive transuranic metallic element; found in trace amounts in uranium ores; a by-product of the production of plutonium Synonym(s): neptunium, Np, atomic number 93
From Webster's Revised Unabridged Dictionary (1913) [web1913]:
Neptunium \Neptu"nium\, n. [NL.] A new metallic element, of doubtful genuineness and uncertain indentification, said to exist in certain minerals, as columbite.
From The Elements (22Oct97) [elements]:
neptunium Symbol: Np Atomic number: 93 Atomic weight: (237) Radioactive metallic transuranic element, belongs to the actinoids. Np-237, the most stable isotope, has a half-life of 2.210^6 years and is a by product of nuclear reactors. The other known isotopes have mass numbers 229 through 236, and 238 through 241. Np-236 has a half-life of 510^3 years. First produced by Edwin M. McMillan and P.H. Abelson in 1940.