Unbinilium

Unbinilium is the temporary IUPAC name for the hypothetical chemical element with atomic number 120. Its symbol is Ubn. As a so-far unobserved superheavy element, unbinilium occupies a position beyond the sixth row of the periodic table and is expected to lie in period 8.

In theoretical models, unbinilium would be placed in group 2, behaving as an alkaline earth metal, and would be predicted to have two valence electrons in an eightteenth shell. Relativistic effects in such high-Z elements make the details of its chemistry uncertain, but many predictions suggest that it would exhibit chemistry related to radium-like elements, with the +2 oxidation state being the most accessible. The actual chemical behavior could deviate from lighter homologs because of strong relativistic stabilization and spin–orbit interactions.

Synthesis and observation: as of the current state of knowledge, there are no confirmed observations of atoms with Z = 120, including unbinilium. Experiments aimed at producing superheavy elements around this region typically involve heavy-ion fusion reactions, but no uncontested production of element 120 has been reported.

Isotopes and stability: theoretical studies consider a range of neutron-rich isotopes of unbinilium, with predicted half-lives generally short due to rapid decay pathways common to superheavy nuclei. Some models speculate that certain neutron-rich configurations near the proposed island of stability could exhibit longer lifetimes, but such predictions remain unconfirmed.

Naming: unbinilium is a systematic placeholder name derived from numerical roots used by IUPAC for undiscovered elements. If and when a definite synthesis is achieved, a permanent name and symbol would be proposed and subject to formal approval.