At this point we've just examined atoms where we're dealing with a neutral element that has the same number of protons and electrons. Now when the number of protons and electrons are different, that's what we go into ions. Ions themselves are created from the loss or gaining of electrons by elements.
So in the creation of an ion or either losing electrons or gaining electrons, we're going to say here when an element loses electrons, it becomes a positively charged ion, called a cation. Now this makes sense. You're losing negatively charged electrons. If I'm losing something negative, I'm becoming more positive.
Now on the other end, when an element gains electrons, so it's gaining negative electrons, it becomes a negatively charged ion called an anion. So just remember, cations are positively charged ions and anions are negatively charged ions.
We're going to say here a new term, isoelectronic. This is when elements have the same number of electrons. So just remember the difference between atoms and ions is that atoms have the same number of protons and electrons. But when we become an ion, we've either lost electrons or gained electrons. This causes a difference in the number of protons and electrons within a given element. So keep that in mind when dealing with ions.