This one is for this one here, from the n equals 5 down to the n equals 2, and that's just three of the possibilities, there is a lot more possibilities, but they don't fall within the visible range. So, the light that we see here has just the right amount of energy for an electron to be going from the n equals 4 down to the n equals 2, so that's from here down to the n equals 2. So, for this photon of light, and the energy associated with that photon of light, it is exactly the right amount of energy for an electron to move from here, the n equals 3, down to, the n equals 2 level, that happens to be the size of that gap. But, every transition will release one photon of light for the energy needed to make that transition, so that's key there. When electron is excited to an outer, spot, let's say it's excited out here to the n equals 5, it can relax back down to the n equal 1 level, now, it can relax back down to any level closer in, so it can go here, an electron from here could go there, an electron could here go all the way down the n equals 1 level. Now the electron would be in its lowest energy if it could be down here in n equals 1, and that's where it wants to be. And n equals 1, n equals 2, n equals 3 here represent where the electron could be and it couldn't be anywhere in between there, so it's not existing here but it could be at 1, at 2, at 3, at 4, and at 5. So, Bohr took that information and started thinking about electrons, and he thought that this could be explained if electrons can only have, very specific energy levels, and this will be re, represented by these orbits that we see going around our nucleus, so here is our nucleus of an hydrogen atom, and we've got our positive proton there. And we know that it's not, every possible wavelength producers, only very specific ones are produced, and there's no way to change where that light shows up on the spectrum. And you could do that for each spot, so we could get the energy of the photon here, we could get the energy of the photon here. Well what he found is if he took, a wavelength there, you could take that wavelength and you could figure out the energy of that photon. So how did Bohr take that information and start developing his, our first understanding, of the atom. Now if you pass white light through the prism, you'd see all the various colors of the rainbow that you see there at the bottom, so we're just producing light at very specific wavelengths. Now here is a helium spectrum, which is different from the hydrogen spectrum, it's got a few more lines, the barium spectrum has even more lines. Here is a schematic of doing it for hydrogen, so you've got the hydrogen gas inside a glass tube on the left hand side of your screen, that tube is then got electrical current passing through it, and that electrical current then is causes it to glow, and once it's glowing, the light is passed through a slit, and focused in on a prism, and then we see the various rainbow separation that's occurring here, so we have, various slides, now this this is the visible range, and there are lines outside of the visible region, and so you could have some film that would develop at those ranges and you would see the different wavelengths of light being produced. That rainbow that is produced, is the spectrum, and you'll have some way of visually seeing that, or electronically seeing that, it is not necessarily in the visible region so I have rainbow in quotes, it could be outside, it could be in the infrared region, it could in the ultraviolet region, it could be in the x-ray region for that matter, so wherever it is you'll see the different wavelengths separated out from each other.
So you might heat it, you might pass electrical current through it, but eventually it will glow, it'll produce light, that light that's produced is passed through a prism.
Now the way you obtained this emission spectra is to energize the sample until it produces light. A line spectra just gives you individual lines at various wavelengths. So what is an emission spectrum? This is a continuous or a line spectra of radiation emitted by a substance, continuous would be like a rainbow seeing all the various colors laid out. Let's begin, with what a hydrogen spectrum is. And we're going to see how this emission spectrum led to our first understanding of the electronic structure in an atom. Now that we've seen the interconnection between photons and electrons, and we've seen how they can interchange their energy, we're going to look at an emission spectrum of a hydrogen atom.
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