Chemistry students in Mr. Bunger’s class are beginning a new unit. Students are learning about how electrons are arranged in atoms of different elements, the different energy levels the electrons are on, and how all of that affects the size of atoms and the way they react with other elements. Mr. Bunger introduced the new unit in a memorable way: with fire. The demo involved lighting potassium, copper, strontium, and sodium on fire and observing the various colors of the flames between the elements.