What defines anions in relation to ion charge?

Anions are defined specifically as ions that carry a negative charge. This occurs when an atom or a molecule gains one or more electrons, leading to an overall negative charge due to the excess of negatively charged electrons compared to positively charged protons. This characteristic is fundamental to understanding chemical behavior, as negatively charged ions (anions) commonly participate in ionic bonds with positively charged ions (cations) to form neutral compounds.

The concept of charged ions is crucial when studying electrochemistry and its applications, such as in facial machines that utilize galvanic currents or iontophoresis. An understanding of ion charges helps practitioners manipulate the behavior of different ions within therapeutic and cosmetic interventions.