In your own words, explain why it is not possible to make primary alkyl halides, such as 1-bromopentane, using the electrophilic addition of HCl or HBr to an alkene.

Electrophilic addition is a reaction where an electrophile reacts with an alkene, resulting in the addition of atoms across the double bond. The reaction typically involves the formation of a carbocation intermediate, which can lead to rearrangements and the formation of more stable, often secondary or tertiary, carbocations rather than primary ones.

Carbocation stability is crucial in electrophilic addition reactions. Secondary and tertiary carbocations are more stable than primary ones due to hyperconjugation and inductive effects. This stability influences the reaction pathway, favoring the formation of more stable carbocations, which leads to secondary or tertiary alkyl halides rather than primary ones.

Markovnikov's Rule states that in the addition of HX to an alkene, the hydrogen atom attaches to the carbon with more hydrogen atoms, while the halide attaches to the carbon with fewer hydrogen atoms. This rule predicts the formation of the more stable carbocation, typically resulting in secondary or tertiary alkyl halides, not primary ones like 1-bromopentane.