Heterolysis is the breaking of a chemical bond in which the shared electron pair goes entirely to one of the two atoms — producing oppositely charged ions rather than neutral fragments. The textbook example is common salt dissolving in water: the ionic bond between sodium and chloride undergoes heterolysis to give Na⁺ and Cl⁻ ions, which water molecules then stabilise. This contrasts with homolysis, where each atom keeps one electron, forming radicals. Heterolysis underpins acid-base chemistry, salt dissociation, and countless reactions in food science — from the ionisation of organic acids that sets a food’s pH, to the behaviour of mineral salts in doughs and brines. Understanding which bonds break how is foundational to chemistry.