Summary:
- Cations are the positive ions formed by the loss of one or more electrons.
- The term isoelectronic refers to an atom and an ion of a different atom (or two different ions) that have the same electron configuration.
- For representative elements under typical conditions, three electrons is the maximum number that will be lost.
- For example, the sodium ion has one valence electron in the third principal energy level.
- Upon losing that electron, the Sodium ion now has an octet of electrons from the second principal energy levels.