If you are planning to become a biologist, a key required course is organic chemistry and in that class one of the reactions you have to memorize is radical halogenation. In this reaction a halogen atom (e.g. chlorine, bromine, iodine) bonds to a carbon and replaces the hydrogen that was formerly bonded to that carbon. When chlorine is used, the process is called radical chlorination. The music video below was created at Columbia University to help students memorize this reaction.