Pb235

Pb-235, or lead-235, is an isotope of the element lead (atomic number 82) with a mass number of 235. If it exists, it would contain 82 protons and 153 neutrons. Pb-235 is not observed in nature and is not among the stable or long-lived isotopes of lead; it would be highly neutron-rich and lie far from the valley of stability.

Nuclear properties and stability: No experimental data exist for Pb-235. Nuclear models predict that such a neutron-rich nucleus would be highly unstable and short-lived. The anticipated primary decay mode would be beta minus emission, transforming a neutron into a proton and producing 235Bi, with further decays along the neutron-rich side of the chart of nuclides. The precise half-life is not known.

Production and experimental status: Pb-235 could in principle be produced in high-energy heavy-ion reactions, such as projectile fragmentation or spallation, or by neutron capture on nearby isotopes, but no confirmed observation has been reported. Searches for extremely neutron-rich isotopes near lead have placed limits on their production cross-sections but have not identified Pb-235.

Context and references: Pb-235 would lie near the neutron-drip line for elements in the vicinity of lead and is of interest mainly to studies of nuclear structure and astrophysical pathways. It has no known practical applications.

See also: Isotopes of lead, Neutron-rich nuclei, Beta decay.