Electron donating groups are generally ortho / para directors for electrophilic aromatic substitutions, while electron withdrawing groups are generally meta directors with the exception of the halogens which are also ortho / para directors as they have lone pairs of electrons that are shared with the aromatic ring.
22.
An "'electron withdrawing group "'( "'EWG "') will have the opposite effect on nucleophilicity as an EDG, as it removes electron density from a ? system, making the ? system more electrophilic aromatic substitution reactions slower and more complex, and EWGs are often called "'deactivating groups " '.
