A simple atomic model for incorporating the effects of chemically-assisted fracture is described. Development of the model is in two parts, which can be formulated independently: lt]o li](i) the crack itself is represented by two elastic semi-infinte chains of atoms, linked transversely by stretchable bonds (quasi-one-dimensional representation); li](ii) the chemical interaction, which takes place at the crack tip atoms, is represented by a classical reaction between two diatomic molecules. While clearly oversimplistic in relation to real structural materials, the approach offers insight into the actual mechanisms of crack-tip chemistry. In particular, the factors which contribute to the generalised force on the crack-tip bond (viz. the applied load, the lattice, and the cohesive force itself) are clearly identified, and conclusions may be drawn in a quite general way about the prospective response of alternative crack systems. The mechanisms of chemically-assisted crack growth under either equilibrium or kinetic conditions are contained naturally in the formalism. Although explicitly set up along the lines of an ideally brittle crystalline cleavage, the model may well be extended to traditionally more complex crack configurations, e.g. as in glasses and metals.