The right and wrong mental models that learners have about the changes in the matter have a great importance in understanding the basis of the chemistry. Therefore, the main purpose of this research was to identify students' misconceptions with regard to physical and chemical change and to come up with models to explain their understanding of this topic. This research was qualitative descriptive with cross-sectional design. The participants were 148 6th graders in Kütahya which is a western city of Turkey. The data were collected through a questionnaire containing five openended questions. Additionally, for a more detailed analysis, 28 participants were interviewed to explore the mental models that emerged. Analysis of responses to the questionnaire generated four mental models (Particle Motion Model, Moving Away Particle Model, Particle Motion+Moving Away Particle Model, Macro Model) for physical change and three mental models for chemical change (Changing Particle Model, Moving Away Particle Model and Macro-Micro Change Model). Implications of these results for chemistry education were discussed. Mental models defined in the research can enable teachers of science and researchers to identify difficulties faced by students regarding physical and chemical changes; thus, they can effectively decide which approach to take on to devise scientific models.