En WiseGEEK podemos leer:

“Ununseptium is a hypothetical chemical element which had not been successfully confirmed by 2008, although several scientific teams had plans for synthesizing it. Despite the fact that the existence of this element has not yet been verified, the scientific community can draw some conclusions about it, and it is safe to say that it really does exist; if it didn’t, the entire periodic table would have to be reworked.” Más en What is Ununseptium?

Pues aquí está presentándose en sociedad: El Ununseptium rellena una casilla en blanco en la Tabla Periódica