# How do you do addition reactions of alkenes?

The first step in the addition reaction, is the interaction between the $\pi$ electrons in the double bond and an electrophile. This leads to the formation of a carbocation intermediate. The intermediate then reacts with the nucleophile present in the medium...
Consider the addition a hydrogen halide $\text{H-X}$ to an alkene:
The first step in the addition reaction, is the interaction between the $\pi$ electrons in the double bond and the H-atom of the hydrogen halide followed by the reaction of the halide with the carbocation intermediate producing an alkyl halide.