Basic Essential Oil Chemistry

The thought of organic chemistry can be daunting, but some knowledge of the basic chemical groups of which essential oils are composed is necessary in order to understand which oils are safe and gentle, and which are stronger or irritating.  Since the chemistry of essential oils is a more advanced topic, I am keeping this as simple as possible.  Further reading on the subject can be found in the books of Kurt Schnaubelt and Marcel Lavabre.  Every essential oil is represented by dominant chemical groups that determine its effects.