Electrons are considered negatively charged due to their intrinsic property called electron negativity, which influences their interactions with other particles. The designation of electrons as negative is arbitrary; historically, current flow was observed before the discovery of electrons, leading to the convention of calling the direction of conventional current positive. Electrons have a smaller mass than protons, resulting in a stronger attraction to positively charged particles. Their arrangement in the electron cloud, particularly in the valence shell, contributes to the overall negative charge, as electrons are in constant motion and paired with opposite spins. This negative charge is fundamental for atomic stability, enabling chemical reactions and molecular formation.