Our theoretical and computational analysis of the chemical reaction delivers understanding its fine details. Here we have presented a systematic review of the utility of the novel tools, accessible with the computational quantum chemistry methods. With the use of the cumulative force constants CAB, the method allows for assessing the bond stability, rather than the bond energy, in some sort of analogy to the standard normal mode analysis. There are two important advantages in our reaction fragility approach over the normal modes evolution along the reaction path: (i) reaction fragilities are given by the electron energy exclusively and