So as I said, there are 4 major types and the first one is the easiest one. This is going to be what we call an acid base reaction, and in most textbooks, this will have its own chapter. So, usually, we will have to spend an entire chapter just talking about acid base reactions. Now the general features of this that you should be aware of are that molecules of opposite charges are going to react together to exchange a proton. Okay? Now I used the word proton earlier in the first chapter when I was explaining just electrons and protons and stuff. And what I said a proton was is just an H⁺. Okay? Because remember that it's a hydrogen that doesn't have an electron and it doesn't have a neutron, so it's just a proton and that's why we call it a proton. Alright? Now notice that I did put the word usually next to it because it turns out that there are going to be some special types of acid base reactions that don't exchange a proton. Alright? But we'll get there. Okay? I'll let you guys know what those are.

So I just want to show you guys this example. This is a very common example where I have basically a negative charge. Okay? So that would be one of the charges and then I'm looking at the other molecule and I see, well, there's no positive charge. So, is this really going to be acid base? Well, if you think about it, we've already learned about electronegativity, right? And remember that we learned how to draw dipole moments. So if I were to look at this HO bond right there, is there a dipole on that bond? And the answer is yes. There's actually a very strong dipole pulling towards the oxygen. So what that means is that more electrons are at the oxygen and fewer electrons are at the hydrogen. Are you guys comfortable with that? That just has to do with the partial charges that we assign. Imagine that the O is like the sumo wrestler pulling on that rope and pulling all the electrons towards itself, and the H is like the puny guy that can't even keep up. Alright? So what that means is that we are going to get an exchange. The oppositely charged hydrogen that I am talking about is this oppositely charged hydrogen. So I have a negative interacting with a positive, and what's going to happen at the end is, remember that I said you get an exchange? So what that means is that I'm going to redraw this first compound and what I'm going to draw is that now this O gets a negative because before the other O had the negative, and now this OH over here is now attached to the H that came from the other compound. Alright? So, basically what happened was that I switched a negative charge and an H. See how that happened? That's what we call an acid base reaction when we're exchanging charges and protons. Alright? And we'll get more into-depth later.