The College Board's recently revised curriculum for advanced placement (AP) chemistry places a strong emphasis on conceptual understanding, including representations of particle phenomena. This change in emphasis is informed by years of research showing that students could perform algorithmic calculations but not explain those calculations using particulate representations. This article provides a discussion of particulate representations in chemistry and specific examples of ways to introduce particulate representations to students and to integrate them throughout the AP chemistry or any introductory chemistry course. This contribution is part of a special issue on teaching introductory chemistry in the context of the advanced placement chemistry course redesign.