Chemistry: Light & The Atomic Model Mini Unit BundleThese lessons are not sold separately because each lesson depends on the previous lesson. The purpose of the unit is to understand how scientists discovered the structure of the atom as we know it today. Otherwise, it will be confusing to students as to why we are stopping in the middle of everything and studying light, the EM spectrum, and calculating wavelengths and frequency! So, essentially, we are traveling down the same road as these scientists