This study aims to determine the topic-specific nature of two experienced chemistry teachers’ pedagogical content knowledge (PCK) in the topics of interactions between chemical species and states of matter. The teachers’ PCK on these topics was investigated in terms of the following components: orientations toward science teaching (OST), knowledge of curriculum (KoC), knowledge of instructional strategies (KoIS), knowledge of learner (KoL), and knowledge of assessment (KoA). Data for the study were collected over five months using multiple data collection tools, including semi-structured
interviews, observations, card-sorting activity, and field notes. PCK is identified in the literature as a topic-specific knowledge. Similarly, chemistry teachers’ PCKs in this study were found to be topicspecific in the topics of interactions between chemical species and states of matter. However, it was
seen that some dimensions of the PCK components were not topic-specific. The results indicated that one of the participants’ OST was topic-specific, while the other’s was not topic-specific. Further, it was determined that the participants focused on abstract nature in the topic of interactions between
chemical species, but they focused on daily life examples in the topic of states of matter. To overcome the students’ difficulties and misconceptions, the participants highlighted abstract nature in the topic of interactions between chemical species and familiar examples in the topic of states of matter. Their KoC differed in terms of relations with other disciplines and curriculum sequence across the topics. Lastly, it was found that the participants’ KoAs consisted of general pedagogical knowledge for both topics. In the light of the results of this study, implications are stated and suggestions on improving the understanding of the topic-specific nature of PCK are provided for in-service chemistry education, pre-service chemistry teacher education, and chemistry education researchers.