15.4 deBroglie Quantum Model

Okay, the last model we're going to look at comes from de Broglie. If you remember, de Broglie's key idea was that if we can think of things that are waves as actually particles moving in a wave pattern, then de Broglie said, "Well, this worked for particles that we think are waves. Are they actually moving in waves?" So, if we've already figured out that it was true for things like an electron going around and in orbits... should be going in a wave. Things that are baseballs being thrown are actually traveling in a wave. Just the wavelength is so small that we don't see the wave pattern. And remember, we still had some problems with Bohr's model. He never addressed the issue of Reliford saying that why did the electrons lose their energy if they don't lose their energy if they're giving off the mr. And some of the other issues were that his formulas only worked for hydrogen, and they see that the emission. lines. Some are brighter than others, so that wasn't really explained. At the time, Niels Bohr didn't realize how much the whole quantum mechanics and his theories could have been linked together. So, he showed that electrons were in orbit, but using de Broglie's idea. Basically, those electrons are traveling in a wave pattern. So, the key thing here is to merge those two ideas together to say, well, maybe the electrons are actually not Really, particles? We're actually thinking of them as waves. So, the quantum model suggests that electrons are actually traveling around in orbit waves. According to de Broglie, the electrons have to be in a certain location based on a distance to actually see it as a complete wave. We know that one complete wavelength goes from start to finish, something like that. So, if we were to put that around in a circle instead of just being in a straight line. Our wave would go up and then we've kind of reflected back downwards like that. So, one complete wavelength would make sort of a circular pattern around the nucleus. If we had two wavelengths, that would basically give us a four-sided shape. But we know that waves, when they hit an object and come back, they sort of reflect up and down. We actually get sort of a standing wave. So, quite often, how we draw these... Things we show the wave in one direction, and then we kind of draw it going in the other direction. So, for one wavelength, it looks sort of like that. If we have four wavelengths, our two wavelengths already would be like four bumps, but it would actually sort of be like another flower sort of shape, but it'd be in between. We know the electron then is going to travel back and forth in these two patterns. So what happens is it has To be a complete wavelength, it has to have the right length. The diagram shows that if it's not the right length, it will not exist. So, the idea of forcing electrons to be at certain energy levels is true. These energies have to match one complete wavelength, they have to wrap around perfectly. And if we think of these as waves, that's fine because remember, particles give off electromagnetic radiation (EMR). If it's an EMR thing like gamma radiation or [Music]. Whatever, but waves don't have to. When we looked at waves in physics 20, a wave could be a water wave, a spring, or whatever. Waves didn't give off electromagnetic radiation (EMR), so if we think of the electron as being a wave, then this whole EMR issue doesn't apply. And this model now works for any material; it doesn't have to be just hydrogen. We can go helium, gold, carbon, whatever. This model would be the same. It's just that you're gonna get more orbits and more wavelengths depending on how... [Music] Many electrons are. So, that's sort of the key idea - that we now think the electrons are more of a wave. And because these waves are going to be going back and forth, around and around, the electron is really not at any one position. It's actually everywhere because it's going super fast and it's going up and down in a wave pattern. So, we actually think of it as sort of being almost like a scribble. So, far nucleus is like that, our electron orbit would actually be a wave. kind of going around and round. If we keep doing this, you can see this sort of makes, kind of a scribbled mess or sort of almost like a cloud. So that's why we call it kind of like the cloud model. There is really no exact location for that electron, but it's gonna be somewhere in that range. And to actually figure it out, we have to use probabilities and things like that. But for your sake, we just have to realize that the electron is traveling as a wave, making sort of this Cloud type model, and this model has now been used for probably about the last hundred years. It's still the current one that we believe to be true, and that's it. So we're back to waves and particles sort of working together at the same time, and that's it for this chapter.