Types of polymers

Molecules that have double and triple covalent bonds are termed unsaturated.
That is, each carbon atom is not bonded to the maximum (four) other atoms; as such, it is possible for another atom or group of atoms to become attached to the original molecule. Furthermore, for a saturated hydrocarbon, all bonds are single ones, and no new atoms may be joined without the removal of others that are already bonded.
Some of the simple hydrocarbons belong to the paraffin family; the chainlike paraffin molecules include methane (CH4), ethane (C2H6), propane (C3H8), and butane (C4H10). Compositions and molecular structures for paraffin molecules are contained in Table 1. The covalent bonds in each molecule are strong, but only weak hydrogen and van der Waals bonds exist between molecules, and thus these hydrocarbons have relatively low melting and boiling points.
Hydrocarbon compounds with the same composition may have different atomic arrangements, a phenomenon termed isomerism. For example, there are two isomers