 Okay, anyway, so let's do this problem. And we're going to use the Rydberg equation a couple of times in this problem. So I'm going to kind of manipulate it to the way I like to set it. So it says, what is the energy difference in kilojoules per mole between the first and second shells of the hydrogen atom if the lowest energy emission in spectral series with n2 equals 1 and n1 equals 2. And then it gives you a wavelength. But I want to calculate that wavelength, okay? So let's just calculate that wavelength and then we'll calculate the energy, okay? And I'll show you where that difference is that we were talking about, okay? So again, you've got to have the Rydberg constant given to you. So you're not going to have to memorize that. You're going to have the Rydberg energy constant given to you, okay? You're not going to have to memorize that. But you do have to know what the Rydberg equation is. So there's the Rydberg equation. And it tells us that it says n2 is 1, okay? So we should be able to figure out the wavelength. And this problem actually gives us the wavelength, but I'm not going to give it to you. So let's see if we get the same answer. Okay, so we'll get the Rydberg constant. But also remember, wavelengths are usually given in nanometers. So you're going to have to convert the means to the quarter, that's 0.75 to nanometers right now. So tens of a negative 9 is 1 nanometer. So that's going to cancel down. And then let's move this up here to run it out of space. So what have we got? 1.97 e7, well times the conversion to nanometers times 0.75. Okay, so I got this answer. I'll take it out to a number of digits because really there's no significant figures in this equation. So that's 8.2275 times 10 to the negative 3. But that's herd nanometer, okay? So you got to watch out about that, right? So if you want to think about it, if you want to think about it on the quick, you want to think about it that way. But if you really are having trouble doing that, you can always erase and be like, it's not, just invert this thing, right? So we say 1 nanometer divided by 8.2275 times 10 to the negative 3. And that should give us our number. They're all product because there it is, 121.5, we'll go to, man. Okay, so it said look for the, I said look for the wavelength. Then if we look at the problem, sure enough, the wavelength is 121.5 nanometers, okay? Just like you would expect, okay? Is everybody okay with that portion of it? Why do you divide it by itself? Because it was per nanometer. Nanometer and per nanometer are not the same thing, right? This is divided by nanometers. So we had to get the nanometers up at the top. So what did you think the inverse to get the 1 over that? So this is this. I've just written it out a little different, okay? It's the same thing. Yeah, but you said that I like flipped the whole answer. You're going to flip it at the end over here, okay? I promise you that's the right answer. I promise you, I wouldn't lie to you. I lied to you before. You don't ever, right? Okay, so are you cool with that? So go through it. If you're having trouble understanding why to flip it here instead of there, you're really doing the same thing, okay? You're just doing it at a different time. I just like to do it step by step by step so it's like people can be like, okay, if I get it, you know, okay? So, and of course, like I said, we've confirmed it. The wavelength is 121.5. So it really is asking us for what's the energy, okay? And like I said, you could go through the whole problem that you got in putting it into Planck's equation and getting your energy done. You could use the Rieberg equation again to get the energy. So can I erase all of this stuff? Is the Rieberg energy constant on this part? Yes. Yeah. All constants, you'll be good. It's really hard to remember all that stuff. I mean, it's good to try to though. So I just write that up because I won't forget it. So now let's change the Rieberg equation to the energy form of it. Sometimes you'll see delta E, that just means the change in energy, okay? When it's the energy, you're going to use the Rieberg energy constant. So you just plug in the same transition, same thing, okay? The Rieberg energy constant is not per joules though. So you don't have to do that flip, okay? Okay. So it's actually much easier and you should get something like negative 1.635 times 10 to the negative 18 joules, okay? It's a very small number like you would expect to get, okay? Why would you expect this to be a small number? Because it's one electron going from one energy level to another energy level, okay? Notice the negative here. That says that it's releasing energy because when you're falling down energy levels, energy is being released, okay? So this makes it more stable when you release energy. If you want to think about it that way, okay? This is the first time we'll be talking about that. But again, this is per one electron, okay? So what you guys were doing the other day was we'll multiply it by Avogadro's number and figure out what per moles of electrons. Every one mole of electrons, we've got 6.022 times 10 to the 23rd. But joules are one mole, okay? But it asks for kilojoules per mole. And you should get this number, negative 96 kilojoules per mole of electrons. So that was probably the numbers that you were getting. And you weren't realizing that you were instead solving for a mole of electrons as opposed to one electron. So I have bad money even though nobody showed me the calculation, okay? Are there any questions about this? So again, this way is really cool because we could figure out well, what's the energy of the electrons that switch it? And the Riberg equation. Alright, Riberg equation, we don't have to plug it back in the points. So if, like, the Riberg or the energy equation is actually going to change if it's negative, does that mean it's going to change? Yeah. Yeah. Because there's going to be a negative times a negative, and that's a positive, right? So that would be where it's going up in energy level. Okay, that makes sense, right? Because it takes energy to climb up a hill if you want to think about it that way. But it doesn't take any energy to fall off, you know, and splash on the ground or whatever. Okay, are we cool with that? Any questions on that one?