Unbiunium

Unbiunium is a hypothetical (theoretical or imagined) element of the periodic table. It is also known as eka-actinium.
Its atomic number should be 121 and it has the symbol Ubu. The name Unbiunium and the symbol Ubu are temporary IUPAC names (meaning "one-two-one" in Latin). This name and symbol exist until a permanent name is decided and the element is created. It is expected to be a F-block element and in a group call the superactinides. It is the third element in the eighth period of the periodic table.
Creation attempts.
The synthesis of unbiunium was first attempted in 1977 by bombarding a target of uranium-238 with copper-65 ions at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany:
No atoms were identified.
Another alternative name is "Lavoisium".