In this study, first the level of interconnectedness of the key concepts concerning the topic of physical and chemical changes in pre-service chemistry teachers' (PSCTs') semantic memories was explored. Second, the group cognitive structures of the PSCTs that contain associations between these key concepts and the response concepts that appeared for the key concepts were mapped. Data for all of these processes were collected by a word association test (WAT). Seventy PSCTs attending the Chemistry Education Department at an education faculty participated in the study. At the end of the study, it was determined that the semantic relatedness that PSCTs established between key concepts in their long-term memories was correct and strong. When the cognitive structure of the PSCTs was mapped based on the key concepts of the topic of physical and chemical changes and the response concepts written for these concepts were examined, it was seen that the links of the key concepts with each other through the response concepts were all suitable in terms of chemistry knowledge. Finally, suggestions are made on how to use the word association method to obtain an overall perspective of the teaching outcomes at the end of the teaching period and/or to quickly reveal the preconceptions of the students before teaching. In addition, recommendations are presented to guide researchers who plan to use this method in terms of the points to be considered during the development of a WAT and the route of development.