The mechanism of the nucleophilic substitution reaction between an alkyl halide and an amine with the displacement of a halogen ion is called the S_N2 Substitution Nucleophilic Bimolecular mechanism. Here's a step-by-step description of the process:1. The nucleophile, in this case, the amine, approaches the alkyl halide from the side opposite to the leaving group the halogen ion . This is because the nucleophile is attracted to the partially positive carbon atom bonded to the halogen.2. As the amine gets closer to the alkyl halide, it forms a partial bond with the electrophilic carbon atom. At the same time, the carbon-halogen bond starts to weaken as the halogen ion begins to leave.3. The transition state is reached when the amine is partially bonded to the electrophilic carbon, and the carbon-halogen bond is partially broken. In this state, the molecule is highly unstable and has a pentavalent carbon atom.4. The amine completes the bond formation with the electrophilic carbon, while the halogen ion fully detaches from the carbon atom, becoming a free halide ion.5. The product is formed, which is a new alkyl amine compound, and the halogen ion is displaced as a leaving group.It's important to note that the S_N2 mechanism occurs in a single concerted step, meaning that bond formation and bond breaking happen simultaneously. This reaction is stereospecific, resulting in the inversion of configuration at the electrophilic carbon center Walden inversion . Factors that favor S_N2 reactions include a good nucleophile such as an amine , a good leaving group such as a halogen ion , and a less sterically hindered alkyl halide methyl or primary alkyl halides .