 Okay, let's start today with this first problem. We'll do both of these, actually, but we'll start with the first one. It says, rank the following radicals in order of increasing stability, right? And those radicals that I'm talking about are these three down here. As you can see, they all have the same molecular formula and same, essentially, overall structure without that hydrogen radical, right? The hydrogens, or the hydrogen radical that's gone. But anyways, they all have the same molecular formula, same, essentially, same structure. And I have written up here the bond association energies of some other structures, right? So you can see here methane, ethane, propane, and isobutane, right? So if you look here, right, it shows the bond association energy. And this is stuff we talked about last lecture, right? The bond association energy for a methyl CH bond is the highest, right? Because the carbon alpha to that carbon-hydrogen bond is going to stabilize that radical, okay? So in fact, it mirrors the stability, remember, of carbocation. So if we've got a methyl, so we call this a methyl radical, amy-radical, right? We've got the primary radical, secondary radical, and here we've got the tertiary radical. And you can see 439 kilojoules per mole, 423 kilojoules per mole, which is less, right? 414 kilojoules per mole and 406 kilojoules per mole. And remember, when we're talking about radical reactions, the radical will abstract the hydrogen from the bond that has the weakest amount of energy, okay? So if we look here, what are we effectively comparing? We're comparing here a primary radical, right, to a tertiary radical to a secondary radical, right? So that's going to kind of mirror or be opposite really of the bond association energy, right? So the stability, remember stability and reactivity are opposites of each other. So whichever one is the most reactive is going to be the most stable radical. Why? Because it's reacting to become more stable, essentially, right? The most stable thing that it can do. So if we look here, probably you guys have already decided which ones they are, right? So which one's the most stable? The middle, right? So this is the most. And which one's the least? To the left. So why? Because that's the primary tertiary. And then of course the middle one is the secondary, right? Yeah, they're both on the end. I know, I know. It's the end for this from you, okay? Okay, are we cool with that one? Everybody's got that one, right? Okay, we're going to record another video. We're just going to change the bottom part, okay?