The purpose of this research was to discuss and reflect about the use of a computer simulation in the learning of intermolecular forces. Simulations are dynamic representations of chemical processes or systems, and allow users to select values for input variables from within suitable ranges and observe the results on output variables. In this study we used free software named “Ligações Intermoleculares”, from http://nautilus.fis.uc.pt/molecularium/pt/ligintermol/index.html. The goal of this activity was to help students build internal representations (mental models) for course content. The research is qualitative. We applied a pre-test and a post-test to a class of students (n=30) from a secondary school trying to find what these internal representations are like. The research indicates that students’ pictographic representations of intermolecular forces improved substantially. These findings suggest that the use of this visual tool helped students to make a better connection between the chemical representations and the macroscopic phenomena presented during a mini-course about solubility.