nep·tu·ni·um /nɛpˈtuniəm, ˈtju-/
□
nep·tu·ni·um /nɛpˈt(j)unɪəm/ 名詞
(abbr.np)拿
neptunium
n : a radioactive transuranic metallic element; found in trace
amounts in uranium ores; a by-product of the production
of plutonium [syn: Np, atomic number 93]
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 2.2*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.