Explain the gaining and releasing of energy by electrons, as related to changes in position relative to one or more atomic nuclei.

For any atom, an electron that is farther from the nucleus contains more potential energy than an electron that is more closely held by the nucleus. At the same time, an electron has more potential energy relative to a large nucleus than it would have relative to a small nucleus. As a result, an electron releases energy if it moves closer to a large nucleus and must absorb energy to be pulled away.