Highlight the electrophilic carbon in red, and highlight the leaving group in blue. Highlight the atom in the nucleophile that will attack the electrophilic center in green. Only atoms need to be highlighted and not the lone pairs or formal charges The image depicts a chemical reaction involving two molecular structures. On the left, there is an alkyl bromide molecule. The structure consists of a carbon chain with a bromine atom (Br) attached to the third carbon. The bromine atom is shown with three lone pairs of electrons represented as dots surrounding "Br".Next to the alkyl bromide is a '+' sign, indicating a reaction.On the right, there is an ethoxide ion. This is represented by a carbon-oxygen bond where the oxygen (O) has a formal negative charge and three lone pairs of electrons (dots around the "O"). The carbon is part of an ethyl group (CH3CH2-).This diagram illustrates a nucleophilic substitution reaction, where the ethoxide ion acts as the nucleophile to displace the bromide ion from the alkyl group.

Answer:Nucleophilic substitution reaction is the characteristic reaction of alkyl halides where halogen atom is the leaving group when the substrate molecule is attacked by a nucleophile.In the alkyl halide, ethoxide is the nucleophile, that attacks the carbon atom bonded to bromine and in the same step, Br starts leaving the substrate. A transition state is built where both ethoxide ion and Br are bonded to carbon and soon ethoxide ion gets completely bonded to carbon and Bromine leaves the substrate as Br- ion. Oxygen atom in ethoxide (nucleophile) circled as green, Bromine (leaving group) circled as blue and electrophilic carbon is circled as red.