I came here from https://www.physicsforums.com/threads/i-dont-understand-how-hcl-is-not-a-ionic-bond.449393/ where replies are no longer allowed. I wanted to reply to suggest a few things: High school students who like chemistry are far smarter than anyone will give them credit for. High school students who don't like chemistry are also far smarter, but they won't show it in chemistry class. If I understand ionic and covalent bonds correctly, it is a largely useless distinction which only serves to confuse the fact that the polarity of atomic bonding falls along a spectrum, not into two neat categories. I also wanted to ask about something I noticed. The chemical known as urea differs from the medicine known as hydroxyurea because a hydrogen atom is replaced by an OH. In water, H is positive and OH is negative. Connected to the carbon atom in hydroxyurea, I imagine the same is true, but that difference in electronegativity pales in comparison to the bond that the carbon atom makes. The fact that Carbon can be either +4 or -4 depending on which electron shell it tries to complete figures into this question, but I haven't asked it yet because I'm thinking with my keyboard. I hope you don't mind. Wouldn't it make sense to say a bond is ionic because our analysis of the electron shells suggests that electrons are shifted from one atom to the other in order to make complete shells, but when that isn't the case (H2, O2, N2, CH4 (in which case we avoid the arbitrary choice of completing all the H's outer shells or the C's outer shell)), it's covalent? That seems a much more useful distinction than all the Linus Pauling stuff I read in that other thread. It identifies convention (do we choose to see the bond as completing electron shells?) rather than some imagined facet of reality as the difference between covalent and ionic bonds. PS With regard to the prefix system, everything is Basic to me. I teach physics to 3-year-olds.