<P> Ionization is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons to form ions, often in conjunction with other chemical changes . Ionization can result from the loss of an electron after collisions with subatomic particles, collisions with other atoms, molecules and ions, or through the interaction with light . Heterolytic bond cleavage and heterolytic substitution reactions can result in the formation of ion pairs . Ionization can occur through radioactive decay by the internal conversion process, in which an excited nucleus transfers its energy to one of the inner - shell electrons causing it to be ejected . </P> <P> Everyday examples of gas ionization are such as within a fluorescent lamp or other electrical discharge lamps . It is also used in radiation detectors such as the Geiger - Müller counter or the ionization chamber . The ionization process is widely used in a variety of equipment in fundamental science (e.g., mass spectrometry) and in industry (e.g., radiation therapy). </P>

What changes when an ion forms from an atom or when an atom forms from an ion