What is the process of adding or removing electrons from an atom or molecule?

The process of adding or removing electrons from an atom or molecule is known as ionization. This process results in the formation of ions, which are charged species that can either be positively charged (cations) if electrons are lost, or negatively charged (anions) if electrons are gained. Ionization is a fundamental concept in chemistry that affects chemical reactivity and interactions between molecules.

Ionic bonding, while related to the transfer of electrons between atoms, specifically refers to the formation of stable compounds through the attraction between oppositely charged ions, rather than the general process of gaining or losing electrons.

Oxidation and reduction are terms that also involve the movement of electrons, but they are specific to chemical reactions. Oxidation refers to the loss of electrons, whereas reduction refers to the gain of electrons. Both processes always occur simultaneously in redox reactions, but they are not the broad term that describes the general process of changing the charge of an atom or molecule through electron transfer. Thus, ionization is the most accurate answer for the question.