Hydrocarbon

Hydrocarbons are grouped into "families" or "homologous series". There are five main families. The hydrocarbons in each family have a general formula and similar chemical properties, and similar trends in physical properties. This system was approved in 1892 by the International Congress of Chemists, meeting in Geneva.

Alkanes are the simplest hydrocarbons. Their general formula is C_nH_2n+2.

Alkenes are similar to alkanes. The main difference between them is that alkenes have a carbon to carbon double bond. The general formula for the alkenes is C_nH_2n.

Note that there is no "Methene". Methene is not possible as alkenes require a carbon-carbon double bond and methane only has one carbon atom.

Alkynes have a carbon to carbon triple bond. C_nH_2n-2 is their general formula.

"Methyne" does not exist because of methane's one carbon atom.

Cycloalkanes are isomers of alkenes. They have the same general formula (C_nH_2n), the only difference is that they do not have a carbon to carbon double bond.

Note that the alkene Ethene does not have a cycloalkane as it can only form a straight line.

Alkadienes have two carbon to carbon double bonds. Their general formula is C_nH_2n-2. They are isomers of Alkynes.

In a similar manner, there can also exist alkatriene (three carbon to carbon bonds) and other forms. The versatile nature of Carbon's chemistry allows for a nearly infinite number of configurations and compounds.

Aromatic hydrocarbons are aromatic organic molecules that form flat ring-shaped bonds. The most simplest of aromatic hydrocarbons are benzene and indole. They can have one ring, heterocyclic, like benzene or 2 rings, bicyclic like napthalene (primary ingredient in mothballs) or many rings, polycyclic like anthracene (red dye colourant). Their general formula is C_nH_2n-6, where n is a number greater than or equal to 6.