Relates in the usual sense to the formal nature of the cleavage of a single bond. If in the bond of the adsorptive
A:
B,
A or
B retains the electron pair, the adsorption is heterolytic dissociative adsorption.
Source:
PAC, 1976, 46, 71. 'Manual of Symbols and Terminology for Physicochemical Quantities and Units - Appendix II. Definitions, Terminology and Symbols in Colloid and Surface Chemistry. Part II: Heterogeneous Catalysis' on page 76 (https://doi.org/10.1351/pac197646010071)