A negatively charged atom is called an anion. Anions are formed when an atom gains one or more electrons. This gain of electrons results in the atom having more electrons than protons, giving it a net negative charge.
For example, when a chlorine atom gains an electron, it becomes a chloride anion (Cl⁻). This process is common in chemical reactions, especially in the formation of ionic compounds.
Understanding anions is crucial in chemistry as they play a significant role in various chemical processes and reactions.