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 a heavier homologue to bismuth and the heaviest member of group 15 (VA). It was first observed in 2003 and about 50 atoms of ununpentium have been synthesized to date, with about 25 direct decays of the parent element having been detected. Four consecutive isotopes are currently known, 287–290Uup, with 289Uup having the longest measured half-life of ~200 ms. On August 27, 2013, researchers at GSI from Lund University in Sweden reported confirming the existence of the element.