 So let's do this one. It says, give the quantum numbers for the third electron in sodium. Okay? So the first thing that I like to do with these ones is to build the electron orbital diagram. Okay? So if you remember, the easiest way to recall how to do that is to write the electron configuration first. Okay? So do you want to help me with the electron configuration? So what is it first? One s. One s. Two. Okay. One s. Two s. No, two s. Two s. Two s. And then two p6. Two p6. And then two s. No, one s. Three s. Three s. One s. One s. Okay? So that's the electron. Learn how to do your electron configuration. So guys. So now we can put our orbitals in order. Like the ladder. Okay? Like we were drawing. So remember, one s is at the bottom. How many orbitals are in the one s sub-level? Right? Just one. Okay? How can we tell? Well, there's only two fit in there. Okay? Next is the two s. Just one orbital. Then the two p. How many orbitals are in that one? Three. Three. And then the three s. Just one. Just one. Okay? Now we want to fill up the electrons. So two, four, ten, eleven. Okay? We have eleven electrons. We better have eleven electrons here. Okay? So how do we fill them up? Remember, off-file principle, tons-rule, poly-exclusion principle. Okay? So up. Up and down. Up. Up. Down. That one's just up. That one's up. Very good. So what was the third electron? So let's count it. One, that's the third electron. So let's just circle that. Okay. In order to remind ourselves, you know, which one we're working with. Okay? So now, what are the quantum numbers? Do you remember what their symbols are? M sub-L. M sub-L. We say M sub-L. Okay? M sub-S. M sub-S. Yeah. Very good. Okay? So, and, do you remember where we get that from? From the principle energy number. Okay? The principle energy level. So since this, since we're looking at this one here, it's in the two. That's M. L. Okay? Remember, L, that's just telling you, this is like angular momentum, we call it. Okay? But it, all it's telling you is, what orbital am I in? Am I in an S orbital, a P orbital, a D orbital, or an F orbital? What orbital am I in? S. S orbital. Okay? So S is always zero. Always zero. So what's L gonna be? Zero. Zero, okay? And remind, remember, M sub-L can only be from plus L to minus L. So what does M sub-L have to be? Zero. Zero as well. Okay? And M sub-S, that just tells us, am I on my feet or am I on my head? Okay? Did I go in first or do I go in second? So which, did this go in first or second? First. First. So this one is going to be positive, right? So plus, okay? And the S is just only the negative half or positive. Yeah, it's either gonna be a negative or a negative one half. Let's do one more, okay? So that one was pretty easy. Let's do a harder one. Maybe one of these P, hopefully I have another color here. Okay, so let's do this one. There. Okay? So what electron is that? Let's just figure it out. So one, two, three, four, five, six, seven, eight, nine, ten. So we're doing the tenth electron. So this was the third electron. Now we're doing the tenth, okay? So N, L, M sub L, and M sub S, okay? So can you tell me what N is? The third. Oh, no, no, the second. So two. Two. Right? So remember, L tells us what type of orbital we're in, right? So what is L gonna be? That's gonna be... Do you remember it? So S is zero. P is the next one. That's where we're in, right? What's after zero? The next number. Next energy. Yeah, so it's one, okay? So it goes zero for S, one for P, two for D, three for F, okay? So P, what is this gonna be if it's a P there? It's gonna be a one. One. So M sub L, what are the numbers that it could be? So it's gonna be... Well, what could it be? It could be one, one, negative one, negative one, or zero. Zero, right? Okay. So remember we labeled... Remember we were labeling these orbitals? Which one would this one be? Do you remember? If you don't, it's alright. No. This one's negative one, okay? Oh, okay. This one's zero, and this one's one. This one's positive, or one, okay? So what is M sub L gonna be then? Where's that electron? Yeah, it's M1. And then the last thing, did that electron go in first or second to that orbital? Second. Second. So what is this gonna be then? It's gonna be... Negative one half, right? Because negatives are the second one. Oh, okay. Okay? Just like you said, the first one comes in as the positive one. Okay? That's how to do that. Questions? I think we probably covered most of them, right? Yeah.