alkánes

Alkanes are saturated hydrocarbons, meaning they consist only of carbon and hydrogen atoms and all carbon-carbon bonds are single bonds. The general formula for acyclic alkanes is CnH2n+2, where n represents the number of carbon atoms. The simplest alkane is methane (CH4), followed by ethane (C2H6), propane (C3H8), and butane (C4H10). As the number of carbon atoms increases, the number of possible structural isomers also increases.

Alkanes are relatively unreactive due to the strength and nonpolarity of their carbon-carbon and carbon-hydrogen single bonds. Their primary reactions are combustion, where they react with oxygen to produce carbon dioxide and water, releasing significant amounts of energy, and halogenation, a substitution reaction that occurs under UV light or high temperatures.

The physical properties of alkanes change predictably with increasing molecular size. Melting points and boiling points generally increase with chain length due to stronger van der Waals forces between molecules. Lower molecular weight alkanes are gases at room temperature, while those with moderate chain lengths are liquids, and larger alkanes are waxy solids. Alkanes are nonpolar and therefore insoluble in water but soluble in nonpolar solvents. They are a major component of natural gas and petroleum, serving as fuels and starting materials for various chemical syntheses.