Many general classes of polymers are formed of hydrocarbons, hydrogen, and compounds of carbon. The polymers are exactly made of carbon atoms bonded together, one to the next, into large chains that are called the backbone of the polymer. We can attach one or more other atoms to each carbon atom in the backbone chain. There are polymers that have only carbon and hydrogen atoms. Polyethylene, polybutylene, polystyrene, polypropylene, and polymethylpentene are examples of these polymers. Polyvinyl chloride (PVC) has a chlorine atom attached to all the carbon backbone. The Teflon has fluorine attached to all the carbon backbone.