theoretical elements

Theoretical elements include only those elements beyond ununpentium (element 115), the rest having not yet been discovered or synthesized. The Periodic Spiral reserves for elements 116 through 117 a place in the seventh period related to the f-block elements; for element 118, a similar place in the noble gases column; and for 119 and 120, respectively, a place with the alkali metals and alkaline-earth metals. (Element 118 and its interim decay product, Element 116, thought to have been discovered in June 1999 by an international research team, were assigned the provisional names ununoctium and ununhexium, respectively, but the team retracted their claim two years later.)