'ununpentium' definitions:
Definition of 'ununpentium'
(from WordNet)
noun
Definition of 'ununpentium'
From: Elements
- Symbol: Uup
- Atomic number: 115
- Atmic weight: 288
- Ununpentium is the temporary name of a synthetic superheavy element in the periodic table that has the temporary symbol Uup and has the atomic number 115. It is placed as the heaviest member of group 15 (VA) although a sufficiently stable isotope is not known at this time that would allow chemical experiments to confirm its position. It was first observed in 2003 and only about 30 atoms of ununpentium have been synthesized to date, with just 4 direct decays of the parent element having been detected. Two isotopes are currently known, Uup-287 and Uup-288, with 288Uup having the longer half-life of ~100 ms.