You’re probably familiar with the concept of atoms. They are the fundamental unit of matter—everything is made up of atoms, which come together in unique ways to form different things. Before you can understand chemical reactions, you must first understand the way that atoms work.
Over the years, scientists have used different models to visualize atoms as our understanding has changed. You may be familiar with a few of the models in Figure 1. In this course, we we largely use the Bohr model.