The main goal consisted in the characterization of gradual concepts according to the categories of physical and chemical processes. The first step was to identify preceding notions about this principle of interaction in daily happenings, followed by the implementation of didactic interventions in order to appropriate the concept, and, finally, the determination of better acceptance of mental representations. This proposal has promoted the comprehension of the universe at macroscopic and microscopic levels and fosters constructive attitudes towards the study of science. This study is based on the corpuscular theory of matter and its interaction with light as a form of energy. The approach is based on a qualitative methodology with a comprehensive - descriptive perspective. A group of twenty-two students was analyzed at a generalized level in the mentioned categories and also, an insightful analysis of three learners with the purpose of determining changes in their cognitive representations. Paralleling the initial test with the final one, it was established that 31.8% of the pupils is placed on the physical - process category, 63.6% on the chemical - process category, and only 4.5% of them does not indicate the interaction; this evidences the progressive conceptual change and the gradual distancing of previous ideas.