Since the H-F forces themselves, as well as their divergences, are readily available in standard quantum chemical computations, the method can be routinely applied for monitoring and imaging changes in reacting systems, traced along a reaction path. For this task we have applied the IRC formalism. The spectrum-like diagrams of changes along a reaction have also been demonstrated for the potential energy of bonded atoms, naturally apportioned as fractions of the potential energy of a system. The method provides description of atoms and their bonds with no need for the common arbitrary definitions assigning atomic volumes or populations. We devote this present article to revealing links between the reaction fragility formalism Application to a chemical reaction within the IRC formalism follows in Section 5. The numerical analysis of the proton migration in formamide molecule has been presented for the sake of illustration the power of the atomic fragility modes in monitoring the role of atoms in a reaction (Section 6).