Atoms like Na and Cl have something in common - they are both very close to having the same set of electrons as a noble gas. one has one too many electrons (Na) and the other is one shy (Cl) when they get close, the Na gives the Cl the extra electron it wants, and now both don't need to interact with other atoms, just the way noble gasses don't need to interact. However they are charged now, and they are oppositely charged, so this means