Delbert Nelson's web space

Burning things is basically breaking stuff apart (often carbohydrates because they make good fuels), while adding oxygen atoms to them (oxidation). Carbon bonded to Hydrogen is like a loaded spring, it feels a bit uncomfortable, while C or H bonded to Oxygen feels quite a bit more relaxed. So, burning causes a lot of stored energy to be released (it's a "fuel"), in the form of heat and light. The color of light produced depends on which atoms are involved: the atoms get "excited" by all the bonds breaking, which means that their electrons get bumped up to higher energy states. When those electrons fall back and release their energy, they correspond to different wavelengths/colors of lights. Check this video for a real ELI5: http://vimeo.com/40271657