The carbon atoms can be in a straight chain or form branches off of the main chain. The more carbon atoms that a paraffin contains the more form different structures it can contain. These different structures of the same compound are called isomers . Isomers have different properties. Paraffins are also known as saturated hydrocarbons because they have the maximum number of hydrogen atoms.
Olefins are chains of carbon atoms which include two carbon atoms attached with a double bond.
These compounds are called unsaturated because they do not have the maximum number of hydrogen atoms. Olefins are not present in crude oil or natural gas but are formed when crude oil is processed in a refinery. These cyclic compounds are called cycloparaffins or naphthenes . These cyclical compounds can be modified even further by removing some hydrogen atoms and joining some of the carbon atoms with double bonds to form aromatics . The most important aromatics are benzene, toluene , and xylene .