Contemporary views on the formation of dynamic nonlinear resonances in isolated intermediate Rydberg quasi molecular complexes formed by a single elementary act upon the slow collision highly excited atoms are discussed. A relation between the emergence of dynamic resonance and the quasi intersection of atomic terms is revealed in the quasi classical approximation. Relationships between the widths of dynamic resonances and the dipole matrix element leading to the corresponding quasi intersections are determined. The physical reasons for the dynamic chaos regime are formulated. A quasi classical statistical description is given of the diffusion ionization of an atomic complex with a dense network of quasi intersections of terms. Development of the stochastic instability of the Rydberg electron trajectories due charge exchange inside the collision complex is considered. The effect the narrowing region of stochastic motion has when passing through the Coulomb convergence of the levels with a simultaneous drop in