Because one of the carbon pairs is double bonded, simple alkenes have 2 fewer hydrogen atoms than alkanes. Ethene Alkynes are the third class of simple hydrocarbons and are molecules that contain at least one triple bond. Like the alkanes and alkenes, alkynes are named by combining a prefix with the ending 'yne' to denote the triple bond. Because carbon can bond in so many different ways, a single molecule can have different bonding configurations. These two molecules are called isomers .
Isomers are molecules that have the same chemical formula, however different structural formulas.
In addition to carbon and hydrogen, hydrocarbons can also contain other elements. In fact, there are many common groups of atoms that can occur within organic molecules, these groups of atoms are called functional groups. One good example is the hydroxyl functional group. The group of hydrocarbons that contain a hydroxyl functional group are called alcohols . The existence of the functional group completely changes the chemical properties of the molecule.