The textbook is aimed at all those interested in communicating chemistry. However, it has been specifically designed for chemistry teacher students, to support them in the preparation and follow-up of their subject-matter didactical studies and in their teaching practice. The specific structures, concepts, and methods of chemistry that are significant for communicating the subject matter of chemistry are analyzed in this textbook from a didactical perspective, guided by theory, and reflected upon in light of classroom practice. At the center of this analysis is the model of transformation, which is used here to highlight the tasks of the chemistry educator. Readers will learn through practical examples how educators can transform the subject matter of chemistry, taking into account the learners and the goals of transformation, into a teaching/learning content, thereby creating effective learning environments. Current challenges complement the foundations and make this book a valuable companion for future chemistry teachers.