Simple hydrocarbons

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The simplest hydrocarbons are those that contain only carbon and hydrogen. These simple hydrocarbons come in three varieties depending on the type of carbon-carbon bonds that occur in the molecule. Alkanes are the first class of simple hydrocarbons and contain only carbon-carbon single bonds. The alkanes are named by combining a prefix that describes the number of carbon atoms in the molecule with the root ending "ane". The names and prefixes for the first ten alkanes are given in the following table.

Carbon Atoms	Prefix	Alkane Name	Chemical Formula	Structural Formula
	Meth	Methane	CH₄	CH₄
	Eth	Ethane	C₂H₆	CH₃CH₃
	Prop	Propane	C₃H₈	CH₃CH₂CH₃
	But	Butane	C₄H₁₀	CH₃CH₂CH₂CH₃
	Pent	Pentane	C₅H₁₂	CH₃CH₂CH₂CH₂CH₃
	Hex	Hexane	C₆H₁₄	...
	Hept	Heptane	C₇H₁₆
	Oct	Octane	C₈H₁₈
	Non	Nonane	C₉H₂₀
	Dec	Decane	C₁₀H₂₂

The chemical formula for any alkane is given by the expression C_nH_2n+2. The structural formula, shown for the first five alkanes in the table, shows each carbon atom and the elements that are attached to it. This structural formula is important when we begin to discuss more complex hydrocarbons. The simple alkanes share many properties in common. All enter into combustion reactions with oxygen to produce carbon dioxide and water vapor. In other words, many alkanes are flammable. This makes them good fuels. For example, methane is the principle component of natural gas, and butane is common lighter fluid.

CH₄ + 2O₂

CO₂ + 2H₂O

The combustion of methane

The second class of simple hydrocarbons, the alkenes, consists of molecules that contain at least one double-bonded carbon pair. Alkenes follow the same naming convention used for alkanes. A prefix (to describe the number of carbon atoms) is combined with the ending "ene" to denote an alkene. Ethene, for example is the two- carbon molecule that contains one double bond. The chemical formula for the simple alkenes follows the expression C_nH_2n. Because one of the carbon pairs is double bonded, simple alkenes have two fewer hydrogen atoms than alkanes.

Ethene

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