Ununseptium is the temporary name of an undiscovered chemical element with the temporary symbol Uus and atomic number 117. It is the only missing element in period 7 of the periodic table. Since it's placed below the halogens it may share qualities similar to astatine or iodine. The first attempt to synthesize this element is currently underway at the Flerov Laboratory of Nuclear Reactions in Dubna, Russia. History Naming The element with Z=117 is historically known as eka-astatine (… (More on Ununseptium)