I brought a little science with me on my last backcountry canoe trip. After a long day of paddling and portaging, I pulled out a tiny bag of metal salts that I had been packing. The goal: to use the salts to create a dazzling light show over the campfire. The colored flames are generated by burning a small amount of a variety of metal salts in the fire. Different metals burn with a characteristic flame color. For example, Cupric chloride emits a blue color and Potassium chloride emits purple.

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So what is happening? >> Thermal energy from the flames increases the energy of electrons in the metal, which raises the electrons to a higher energy state. The electrons cannot spend a lot of time in the excited state and so release energy as light in order to return to a more stable state. The light released are the colored flames we see in the fire, characteristic to the specific metals. Cool!