Electron withdrawing groups (EWGs) are atoms or groups of atoms that pull electron density away from the rest of a molecule through inductive or resonance effects, making the molecule more electrophilic. They play a crucial role in influencing the reactivity and stability of compounds, especially in organic chemistry reactions such as electrophilic aromatic substitution and nucleophilic substitution reactions.
Reactivity refers to the tendency of a substance to undergo chemical reactions, either by itself or with other materials, which is influenced by factors such as electron configuration, temperature, and pressure. Understanding reactivity is crucial in predicting the behavior of substances in various environments and in designing chemical processes and materials.