The purpose of this study is to identify how upper secondary school French students (Grade 10-12) interpret chemical transformation with regards to the changes within molecules and atoms, and in terms of intramolecular and/or intermolecular bond breaking. In order to identify and describe the students' assimilated knowledge, four questions were asked to 930 students using a written questionnaire submitted a long time after the related teaching took place. There is much research into student learning in the concept areas discussed here (atoms and molecules, chemical change, chemical bonding), as reviewed in the paper. The present study presents data from an educational system where limited work has been reported in the international literature. The French system has its own unique curriculum, and is taught in the national language (where much of the existing research has concerned learning in Anglophile systems). The research reported here found that French secondary students experienced many similar difficulties in understanding these key scientific concepts to those that have been reported elsewhere, showing the cross-cultural nature of the key educational issues. For example, many have difficulties in understanding the changes undergone by atoms and molecules in the course of a chemical reaction; many are not able to justify explicitly the breaking of inter-molecular bonds and to interpret the breaking of intramolecular bonds in terms of reorganization of atoms, the target level of understanding in the curriculum from the end of Grade 9. However, it is also suggested that some of the specific characteristics identified here are linked to the ordering and language used in the French curriculum, and such cultural idiosyncrasies may offer useful insights into both problematic and valuable aspects of science pedagogy. (Contains 4 figures and 7 tables.)