Sb71

Sb-71, or antimony-71, is a hypothetical isotope of the element antimony (atomic number 51) with mass number 71. It would be an extremely neutron-deficient nuclide for antimony and lies far beyond the proton drip line, the boundary beyond which nuclides are not bound against proton emission. There is no experimental evidence for the existence of Sb-71, and it is not listed in standard nuclear data tables.

Because Sb-71 would be highly proton-rich, it is expected to be very unstable. If it could exist, its binding energy would be insufficient to sustain a bound state, implying an exceedingly short lifetime. In such proton-rich systems, decay is typically dominated by rapid proton emission and/or beta-plus decay to lighter nuclides. However, precise decay modes and half-lives for Sb-71 are unknown due to the lack of observational data.

Any potential production of Sb-71 would require high-energy nuclear reactions, such as projectile fragmentation or fusion-evaporation processes in accelerator facilities. To date, no experiments have observed Sb-71, and its status remains purely theoretical. The concept of Sb-71 helps characterize the limits of nuclear stability in the region around antimony, illustrating how certain combinations of protons and neutrons are not sustainable in bound nuclear matter.