The following PowerPoint introduces students to various atomic models discussed over the centuries. Starting with Democritus, the idea of the atom was philosophically discussed as the smallest unit of matter. John Dalton revived the idea centuries later. During the late 1800s and early to mid 1900s, numerous models were developed as subatomic particles were discovered. The current model of the structure of matter relies on two groups of fundamental particles (quarks and leptons) and four forces of nature.

A key theme is the changes in explanations of the atom as new data are collected.

Important: Please read the presenter’s notes for specifics not discussed on the slides. For clarity, Ernest Rutherford was not awarded the Nobel Prize for the development of the “solar system” atomic model but for his work in radioactivity.