Question

sketch a diagram showing the potential energy surface for a generic sn2 reaction​

Answer 1

S_N2 indicates a substitution, nucleophilic, bimolecular reaction, described by the expression rate = k [Nu][R-LG].
This implies that the rate determining step involves an interaction between two species, the nucleophile and the organic substrate.
This pathway is a concerted process (single step) as shown by the following reaction coordinate diagrams, where there is simultaneous attack of the nucleophile and displacement of the leaving group(x).The nucleophile attacks at the carbon with the partial positive charge as a result of the polar s bond to the electronegative atoms in the leaving group.Single step reactions have no intermediates and a single transition state (TS).

In an S_N2 there is simultaneous formation of the carbon-nucleophile bond and breaking of the carbon-leaving group bond, hence the reaction proceeds via a TS(transition state) in which the central C is partially bonded to five groups.