An anion is an ion with a negative charge, meaning it has more electrons than protons. Anions are formed when an atom gains one or more electrons. In contrast, a cation is an ion with a positive charge, meaning it has fewer electrons than protons. Cations are formed when a metal loses its electrons. The main differences between cations and anions are:

• Charge: Cations have a positive charge, while anions have a negative charge.

• Electrode attracted to: Cations are attracted to the cathode (negative electrode), while anions are attracted to the anode (positive electrode).

• Type of element: Cations are formed by metal atoms, while anions are formed by non-metal atoms.

Examples of cations include calcium (Ca2+), potassium (K+), and hydrogen (H+), while examples of anions include iodide (I–), chloride (Cl–), and hydroxide (OH–).