In this study, we present an atomic decomposition, in principle exact, at any point on a given reaction path, of the molecular energy, reaction force and reaction flux, which is based on Bader's atoms-in-molecules theory and on Pendás' interacting quantum atoms scheme. This decomposition enables the assessment of the importance and the contribution of each atom or molecular group to these global properties, and may cast the light on the physical factors governing bond formation or bond breaking. The potential use of this partition is finally illustrated by proton transfers in model biological systems.