So this donates a pair of electrons. This accepts a pair of electrons. So our intermediate reactants are the intermediate carbocation that has a positive charge on this carbon and has an extra h that it got from the hydrochloric acid. Now, this chlorine, or chloride atom now has an extra pair of non bonding electrons, and so it develops a negative charge. In the second step of this addiction reaction, we have the chloride ion donating a pair of non bombing electrons. So this is our lewis base and our lewis acid.