hypothetical chemical element with the atomic number 119

Ununennium, or element 119, is a chemical element. Its symbol on the periodic table is Uue. Ununennium and Uue are substitute names made by the IUPAC, until permanent names are made. Ununennium is the element with the smallest atomic number that has not been created yet. Qualities of Ununennium are unknown, but many are predicted. It is predicted all isotopes will be radioactive. It may be an alkali metal.[1]

Many attempts have been made by American, German, and Russian teams to make ununennium but none have worked. Japanese and Russian teams plan to work on it in 2019 and 2020. Ununennium's spot on the periodic table is a sign that it may be similar to lighter elements such as lithium, sodium, potassium, rubidium, caesium, and francium; however, some of its properties may be different from what is expected. For example, ununennium might be less reactive than caesium and francium and will behave more like potassium or rubidium. As of 2017 it is unknown but Ununennium's only use will probably be for research purposes.


  1. "Transuranium element". Encyclopedia Britannica. Retrieved 19 September 2017.