Ununennium (AKA eka-francium) is an udiscovered element with the symbol Uue and the atomic number 119. Wikipedia has an article, "Ununennium" about the element. That article stresses synthesis of the element and its chemical & atomic properties.
It has yet to be physically made in a lab like Oganesson and Tennessine. Physicists say Uue is difficult to synthesize because it has a small fusion cross-section. What that means is that when target and projectile nuclei fuse, the compound nucleus simply fissions immediately. It is rare for the compound nucleus to shed its extra energy by emitting neutrons. Only a few laboratories, notably FLNL in Russia, GSI in Germany, and RIKEN in Japan, have the ability to find those rare surviving nuclei.It is known that it is the first element with an electron in the 8s orbital. Its position in the first column suggests that it does have similar properties to the alkali metals, lithium, sodium, potassium, rubidium, cesium, and francium; however, relativistic effects may cause some of its properties to differ from those expected from a straight application of periodic trends. For example, ununennium is expected to be less reactive than cesium and francium and be closer in behavior to potassium or rubidium, and while it should show the characteristic +1 of the alkali metals, it is also predicted to show the +3 oxidation state unknown in any other alkali metal.