The flow of electrons provides a more dynamic picture of the changes occuring between the left and right hand side of the equation. The result is the substitution of the nucleophile for the leaving group. This also is consistent with a single step in which the nucleophile replaces the leaving group. This is true if the nuclephile is charged. If the nucleophile is neutral and the product charged, then more polar solvents will speed up S N 2 reactions.
Solvents can also modify nuclephilicities, as mentioned above.
The stereochemistry at the carbon atom substituted is racimized . The more stable the resulting carbocation, the faster the reaction. 1 o , in other words, the more substituted a carbocation, the faster the reaction. E 1 is fastest for tertiary substrates or others forming stable carbocations. The position of the double bond in the product is determined by which of the alpha hydrogen atoms is removed along with the leaving group.