Hydrocarbons

In organic chemistry, a **hydrocarbon** is an organic compound consisting entirely of hydrogen and carbon .Hydrocarbons from which one hydrogen atom has been removed are functional groups , called **hydrocarbyls**. Aromatic hydrocarbons (arenes), alkanes, alkenes , cycloalkanes and alkyne -based compounds are different types of hydrocarbons. The majority of hydrocarbons found naturally occur in crude oil, where decomposed organic matter provides an abundance of carbon and hydrogen which, when bonded, can catenate to form seemingly limitless chains.

=Hydrocarbons=
 * Hydrocarbons are the simplest [|organic compounds] . Containing only carbon and hydrogen, they can be straight-chain, branched chain, or cyclic molecules. Carbon tends to form four bonds in a tetrahedral geometry.[|Hydrocarbon derivatives] are formed when there is a substitution of a[|functional group] at one or more of these positions. || [[image:http://hyperphysics.phy-astr.gsu.edu/hbase/organic/imgorg/hydrocarbon.gif align="center"]] ||

Usage
Hydrocarbons are one of the Earth's most important [|energy resources]. The predominant use of hydrocarbons is as a combustible [|fuel] source. In their solid form, hydrocarbons take the form of asphalt. [|[12]] Mixtures of volatile hydrocarbons are now used in preference to the [|chlorofluorocarbons] as a [|propellant] for [|aerosol sprays], due to chlorofluorocarbon's impact on the [|ozone layer]. [|Methane] [1C] and [|ethane] [2C] are gaseous at ambient temperatures and cannot be readily liquefied by pressure alone. [|Propane] [3C] is however easily liquefied, and exists in 'propane bottles' mostly as a liquid. [|Butane] [4C] is so easily liquefied that it provides a safe, volatile fuel for small pocket lighters. [|Pentane] [5C] is a clear liquid at room temperature, commonly used in chemistry and industry as a powerful nearly odorless [|solvent] of waxes and high molecular weight organic compounds, including greases. [|Hexane] [6C] is also a widely used non-polar, non-aromatic solvent, as well as a significant fraction of common [|gasoline]. The [6C] through [10C] alkanes, alkenes and isomeric cycloalkanes are the top components of gasoline, naphtha , jet fuel and specialized industrial solvent mixtures. With the progressive addition of carbon units, the simple non-ring structured hydrocarbons have higher viscosities, lubricating indices, boiling points, solidification temperatures, and deeper color. At the opposite extreme from [1C] methane lie the heavy tars that remain as the //lowest fraction// in a crude oil refining retort. They are collected and widely utilized as roofing compounds, pavement composition, wood preservatives (the creosote series) and as extremely high viscosity sheer-resisting liquids.