Electrolytes are ions that form when salts dissolve in or fluids. These ions have an electric charge. Positively charged ions are called cations. Negatively charged ions are called anions. Electrolytes are not evenly distributed within the body, and their uneven distribution allows many important metabolic reactions to occur. (Na ), Potassium (), (Ca2+), (Mg2+ ), chloride (Cl-), phosphate (HPO42-), bicarbonate (HCO3-), and Sulfate (SO4-) are important electrolytes in humans.