Why do alkenes undergo addition reactions more readily than alkanes?

Alkenes undergo addition reactions more readily than alkanes due to the presence of a reactive double bond.

Alkenes are hydrocarbons that contain a carbon-carbon double bond. This double bond is not only a region of high electron density, but it is also a region of high reactivity. This is because the double bond is made up of one sigma bond and one pi bond. The pi bond is weaker and more exposed than the sigma bond, making it more susceptible to attack by electrophiles, which are species that are attracted to regions of high electron density.

On the other hand, alkanes are hydrocarbons that only contain single bonds between carbon atoms. These bonds are stronger and less reactive than the double bonds found in alkenes. Alkanes are saturated hydrocarbons, meaning they contain the maximum possible number of hydrogen atoms for the number of carbon atoms present. This saturation makes them relatively unreactive, especially in comparison to alkenes.

The reactivity of the double bond in alkenes allows them to undergo addition reactions more readily than alkanes. In an addition reaction, the double bond of the alkene is broken, and new atoms or groups of atoms are added to the carbon atoms. This is different from alkanes, which typically undergo substitution reactions, where one atom or group of atoms is replaced by another.

In summary, the presence of a reactive double bond in alkenes makes them more prone to addition reactions, while the single bonds in alkanes make them less reactive and more likely to undergo substitution reactions.