 Okay, so these two were the two isomers of C4H10, right, and they were structural isomers. Let's just go ahead and erase this one here, okay, and talk more in depth about this one here. In fact, we're going to talk about conformational isomers now, okay? So remember, structural isomers occur when you've got two molecules that have the same molecular formula, but you've got a break of bond and reform of bond, okay, to make everybody cool with that, right? So, conformational isomers are a little different, are a lot different than that. Confirmational isomers are actually the same molecule in different positions, okay? So, it's like I'm the same person if I go like this or like this or like this, okay? Just like butane here, right, that thing, right now it looks like a Charlie Brown, right? Let's look at its bond line structure, right? So we've got that, but we can imagine twisting because you can rotate around single bonds, okay? So this is a single bond, right? So we can imagine doing what we call a rotation around that single bond, a conformational rotation. And if we now drew the bond line form, it would look like that, okay? Let's just, let's just do it with our model because it helps out, I promise you, wouldn't you do it with a model, right? So what are we doing? We're rotating around that carbon-carbon middle single bond, right? Now it looks like this other thing, right? Okay? Notice we did not break a bond and make a bond, right? So I could ask you this question and hopefully you'd answer it correctly. Is this molecule the same molecule as this molecule? Yeah, because all I did was something like this. As opposed to that, you know what I'm saying? I just moved, you know? I'm the same thing. So you can imagine it. Moving like this, like this, like this, like this, right? Like this, like this, whatever, you know? In fact, that's what molecules do, okay? And we'll talk about it later, probably not in this glass, but in a later chemistry class when you take it. We'll talk about, you know, the barrier of rotation between, you know, how much energy it actually takes to rotate around that single bond. And why we prefer to draw it in this way, because this way is actually more quote-unquote stable, okay? So it's actually got a less overall energy than this way. Why? Because notice what we call, we got steric hindrance here. You can see it real well with the model, right? Those hydrogens will bump into each other, okay? So when that happens, that's not good, okay? They don't like to bump into each other. So that's going to be energetically unfavorable, okay? Relative to the Charlie Brown type of structure. Okay. Does that make sense? Okay, so that's conformational isomers. They're the same molecule. They just switched in a different position. Are there any questions about that? Okay, cool. You guys are doing really well.