'Neptunium' definitions:
Definition of 'neptunium'
(from WordNet)
noun
A radioactive transuranic metallic element; found in trace amounts in uranium ores; a by-product of the production of plutonium [syn: neptunium, Np, atomic number 93]
Definition of 'Neptunium'
From: GCIDE
- Neptunium \Nep*tu"ni*um\, n. [NL.] A radioactive metallic element of atomic number 93, produced in nuclear reactors from Plutonium or Uranium. Symbol Np; The atomic weight of the most stable isotope is 237.0482. [PJC]
Definition of 'neptunium'
From: Elements
- 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 2.2*10^6 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 5*10^3 years. First produced by Edwin M. McMillan and P.H. Abelson in 1940.