Finally: Just what is the difference between a molecule and an ion?! I'm going nuts... And I don't like the simplified explanation that polyatomic ions can have a differing amount of electrons in comparison to their protons and molecules can not. I don't understand this explanation because molecules can consist of polyatomic ions?
Some of your definitions aren't very good.
Atoms and molecules: electrically neutral.
Ions: electrically charged.
A polyatomic ion is exactly like it sounds: basically a molecule that has an overall charge may be considered a polyatomic (more than one atom) ion. The simplest ions consist of a single atom where the charge of the nucleus either exceeds or is exceeded by the total charge of the surrounding electrons. In chloride, Cl-, for example, the nucleus has 17 protons and there are 18 electrons surrounding it, for an over all charge of -1. In the chlorine atom, the 17 protons in the nucleus are balanced by 17 electrons, for an overall charge of 0. An example of a polyatomic ion is nitrate, NO
3-. This ion consists of three oxygen atoms and nitrogen bound together, but the structure has one more electron than the total number of protons in the system, for an overall charge of -1. This charge is not necessarily totally located near one atom; rather it may be spread over the entire ion.
Because polyatomic ions are charged, their properties are quite a bit different than those of molecules, which are electrically neutral. Also, ions are always accompanied by another ion with an opposite charge, as in sodium (Na
+) nitrate (NO
3-). In this case, the sodium ion is a simple cation, whereas the nitrate anion is polyatomic.