The nucleophile attacks the electrophile, which is typically a carbon atom bonded to a leaving group, facilitating the substitution.

S_N2 reactions result in inversion of configuration at the chiral center due to the backside attack of the nucleophile.

The rate-determining step is the slowest step in a reaction mechanism, which controls the overall reaction rate.

The addition of HBr follows Markovnikov's rule, leading to the formation of 2-bromopentane as the major product.

The S_N2 reaction will invert the configuration, resulting in the (S) configuration for the product.

This reaction is a substitution mechanism (S_N2 or S_N1) where the nucleophile replaces the halide.

Dehydration of an alcohol results in the formation of an alkene by the elimination of water.

Tertiary alkyl halides are most favorable for E2 reactions, but primary and vinyl halides can also undergo E2 under certain conditions.

S_N1 reactions are favored by tertiary substrates due to the stability of the carbocation intermediate formed.

S_N2 reactions are bimolecular and involve a direct attack by the nucleophile, leading to a concerted mechanism without a carbocation.

E2 reactions occur in a single concerted step where the base abstracts a proton while the leaving group departs.

E2 reactions require the leaving group and the hydrogen to be anti-periplanar for the elimination to occur.

E1 reactions proceed through a carbocation intermediate and are not stereospecific, unlike E2 reactions.