The interaction between dissociation/recombination chemical processes and the internal energy modes in a simple diatomic molecule is studied in detail. A generalized expression dependent on the initial distribution of recombining molecules is obtained for the rate constants under nonequilibrium conditions. Special cases of the resulting models match the standard Marrone and Treanor models. An initial recombination distribution using information theory is derived from first principles assuming that molecules behave as rotating Morse oscillators with rotation and vibration coupled. This exercise is carried out explicitly for oxygen, and application to nitrogen, nitric oxide, carbon monoxide and the electronically excited states of oxygen is shown to be much the same. A thermally averaged distribution is obtained to describe the initial recombination distribution at different temperatures. A general non-dimensional expression for the initial recombination distribution is presented for all the molecules considered. Special case of this thermally averaged distribution matches well with the initial recombination distribution obtained empirically by Marrone and Treanor.