What is the process called when an atom gains or loses electrons to become charged?

The process by which an atom gains or loses electrons to become charged is known as ionization. When an atom loses one or more electrons, it becomes positively charged, forming a cation. Conversely, when it gains electrons, it becomes negatively charged, resulting in an anion. This transformation into charged particles, or ions, is central to many chemical reactions and interactions in nature, particularly in the formation of ionic compounds and in the behavior of atoms in solutions.

The other options refer to different concepts. Electrolysis is a chemical process that uses electric current to drive a non-spontaneous reaction, typically for the purpose of breaking down compounds. Ionic bonding describes the electrostatic attraction between oppositely charged ions, which occurs after ionization has created these charged species. Electron affinity refers to the energy change that occurs when an electron is added to a neutral atom, but it does not specifically address the overall process of an atom becoming charged through gaining or losing electrons.