The stability of elements decreases as the atomic number increases. no stable elements have been discovered with atomic numbers greater than 118 (Oganesson).
Elements beyond atomic number 118 are highly challenging to produce and study due to their extreme instability and short lifetimes. These superheavy elements tend to have very short half-lives, making it difficult to observe their properties or study them in detail.
However, it is theoretically possible that an undiscovered element with an atomic number greater than 120 could exist and be stable. The stability of such an element would depend on its nuclear structure, including the balance of protons and neutrons in its nucleus. Theoretical models and predictions suggest the existence of an "island of stability" in the region of superheavy elements, where elements with certain combinations of protons and neutrons could exhibit enhanced stability and longer lifetimes.
Scientists are actively engaged in theoretical calculations and experimental efforts to explore the potential existence and properties of superheavy elements. Future discoveries may shed more light on the stability of elements beyond atomic number 120 and the possibility of finding stable isotopes in that region.