Serving as an introduction to atomic structure, this lesson on the Changing Atom includes all the materials needed for a group activity on the contributions of key scientists to the development of the theory of atomic structure. It features an interactive PowerPoint including starter, group activity, questions and plenary along with a worksheet and a lesson plan. This is the first lesson in a series covering the OCR AS Chemistry specification and relates to the following sections: Module 2 – Foundations in chemistry Part 1 – Atoms and reactions 2.1.1 Atomic structure and isotopes Please review! Content covered How Science Works - HSW7 - The changing accepted models of atomic structure over time. The contributions of five scientists to the development of the theory of atomic structure. Duration : One part lesson (setting up) and one whole lesson (group activity and plenary). The rest of the part lesson can be spent starting atomic structure (see atomic structure lesson) Links Next lesson – Atomic structure Bundle covering the whole of the OCR A level chemistry specification sections 2.1.1 and 2.1.2. (topics 1-4) https://www.tes.com/teaching-resource/atomic-masses-formulae-and-equations-ocr-as-chemistry-12348685