Ununseptium is a placeholder assigned until the element has been given a final name. As of late 2006 it is the only element through 118 whose discovery has not yet been claimed.

Ununseptium is the superheavy artificial chemical element with temporary symbol Uus and atomic number 117. The element, also known as eka-astatine or simply element 117, is the second-heaviest of all the elements that have been created so far and is the second-to-last element of the 7th period of the periodic table. Its discovery was first announced in 2010� synthesis was claimed in Dubna, Russia, by a joint Russian-American collaboration, thus making it the most recently discovered element.

t 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.