 Okay, so let's talk about a reaction like this one here, where we've got, well clearly, is this an exothermic or endothermic reaction? Exothermic. Why do you know that? Because the projects are at a lower pi than the reactants, right? So, let's go ahead and draw the reaction coordinate, so we'll call this reaction progress or something like that, and we'll use this to be like, well, we'll just say overall energy, okay? And remember, G is Gibbs free energy, so that's the energy of the whole system. Okay, here we have the reactants here. In this case, it's O3 plus O, and then we've got the products down here, 202, okay? So remember, reactions can be, they're like camels, you know, so they're one-humps. That's like a Mike Tyson reaction, just walk up and knock the guy out, okay? So this is one of those one-hump reactions, right? So, one step we call those reactions, that's the step, okay? So remember here to here, if we're talking about G, right, is going to be what? Delta G. Delta G, right, because that's the difference between the reactants and the products. In this case, Delta G is going to be positive or negative? Negative, right? Why? Because the reactants have more internal energy than the products do. So, they need, the excess energy needs to be released, and that's being released in this case as heat. That's what it's saying, okay? So up here, we've got what's called the transition state, okay? Ts, or activated complex, some people call it. It's drawn up there, you can kind of see it. You can see this is not really a molecule, it's not really an antifreeze, okay? That's another one. That is another one. Okay, sorry about that. So, you can see what's happening is the O3 molecule, which is like this portion here, right? It's reacting with the O molecule or O-atom, which is that portion there. But what's happening is we're making this molecule here, O2, and these bonds aren't really broken or worn, okay? So it's not an actual molecule, okay? It's just like some, you know, temporary state, okay? It's not anything you can actually isolate. But that energy from there to there is called the activation energy. We've been using EA, okay? You also might see it as delta G and double dagger, it's called, okay? So if you can't see that symbol, it says delta G. I don't know if there's really anything else about this that we want to talk about. So just remember, transition state, if there was, if this was a 2-hump, there would be an intermediate. And we'll talk about those instead, okay? Any questions on that one?