Specific features are considered and an analysis is performed of the influence of the long-range dipole interaction on the efficiency of ionization processes in slow collisions of excited atoms with values of the principal quantum number 3 < n < 25. It is shown that the configuration mixing, which disturbs the selectivity of initial excitation, can lead to the formation of new reaction channels. It is noted that in the case of slow collisions, for systems with a small number of degrees of freedom, the stochastic dynamics of valence electrons can have a significant effect, during a single collisional event, on the efficiency of physicochemical reactions because of the appearance of internal resonances in the excited quasi-molecule.