Absorption of Light - Video Tutorials & Practice Problems
On a tight schedule?
Get a 10 bullets summary of the topic
Atomic Absorption & Emission
1
concept
Atomic Emission
Video duration:
7m
Play a video:
Video transcript
So here we talk about the ideas of a mission versus absorption. Now, absorption involves the taking in of excess energy by an electron or an atom and promoting itself to a higher energy state. So here, if we're going by boards model of the hydrogen atom, we have our electron here in the first shell of the hydrogen atom here. This is ambient outside energy that it absorbs it takes in this outside energy and uses itself, uses it to drive itself up to a higher energy state, we'd say when it absorbs it gets to an excited state, however, you can't hold onto that excess energy forever and eventually you have to let it go when it releases that excess energy that it absorbed earlier, it's going to emit that energy and drop back down to its ground state. Now we can talk about the movement of an electron from one shell to another shell and the type of energy involved in either absorption or emission. Now we're going to say if we're talking about emissions, we could talk about emission line spectrums here. They each have different names. We can say that the number of shells were at the moment. We can go up to seven based on the periodic table. There are seven rows on the periodic table. So we can talk about elements having seven shells, but remember the periodic table is not static. It's dynamic as we discover new elements as we explore space. Maybe when we get to mars we find something new or maybe we come up with more advanced technology that allows us to create more synthetic elements in the lab. The number of shells can greatly expand beyond seven, maybe in 100 years. There'll be an additional row or two. That's the way the periodic table works for Now. We're talking about these particular emission line spectrums meaning that our electron or are excited atom drops from a higher shell number to its original ground state and depending on where it lands, it has a specific name to it. So if you're going from a higher shell number, whatever it is, you're dropping back down the shell number one, which is your original ground state. We call that a Lineman series. Now in terms of electromagnetic radiation alignment series would fall within the U. V. Spectrum of our electromagnetic spectrum. The bomber equation from the bomber series. You're going from a higher shell number and you're dropping down to the second shell. We're going to say here, you're going to basically emit light in the visible light region. This type of emission we can see because it falls within the part of the electromagnetic spectrum that we can see without the aid of any technology, we can use our eyes. Passion series. We're going from a higher shell number down to shell number three. This falls with an IR and in fact, the next to all fall within IR. Finally, the Humphrey series falls closer to microwave region. So we're gonna say this one's closer to the microwave region of the electromagnetic spectrum, remember distance equals energy as we can see if you're going from the second shell down to the first shell. This is the distance you have to traverse going from the third shell down to the second shell. This is the distance third shell to the second shell. That's the distance you can see as you go higher up with the shell numbers, the distance between shells get smaller and smaller. So we can say that in terms of energy it's increasing going this way. Because whatever shell this is when we drop down to the first shell, that's a big distance to cover. If this isn't too. And it's one of the even larger numbers, then it's an even greater distance you have to fall. We can say in terms of this chart that we have our potential energy, we can see our potential energy equals R Rydberg constant, which is negative 1.8 times 10 to the negative 18 jewels times one over and squared. So you can figure out the potential energy your electron has in each shell. Now we sit at the bomber series deals with the visible light spectrum in terms of its emission from this, we have what are called emission spectrums and absorption spectrums. Now, if we're dealing with, let's say we're dealing with a cloud here. Okay, we're gonna say here for an emission spectrum. It represents the different frequencies of electromagnetic radiation emitted by an atom as it transitions from a higher energy state to a lower energy state. Here we have a cloud of particles and we can say that this cloud of particles is it has a higher than normal temperature. And we're gonna say that emits certain forms of radiation as the electrons or atoms fall down to a lower energy state. These bits of energy are filtered through this slit and pass through this prism. And from this we're able to come up with an emission spectrum in an emission spectrum. We have a black background and on it are projected strips of colors. By analyzing the strip colors here, we can identify the element that we're dealing with because different elements produce slightly different emission spectrums. Now, what's the difference between that and an absorption spectrum? Well, in an absorption spectrum, things are inverted. Now we have a colored background which represents the visible light spectrum. And then we have these black bands here that we can look at to help us identify our unknown element here. In this case we have some type of energy source that passes through an atom cloud and electron and then that is passed through the slit and then through a prism to help create this absorption spectrum. So the difference between an emission spectrum and and an absorption spectrum is how it looks. But really how the energy is filtered through the slit. Then through the prism here the energy comes directly from a cloud of particles in an atom itself that's excited and it gets pushed into the slit and then to the prison to create this emission spectrum for an absorption spectrum. Its first filtered through a atom outside energy source filters through the atom, which then filters through the slit to get to the prison. To create an absorption spectrum. Just remember fundamentally absorption means you're taking an energy to jump up to a higher energy state emission. You release that excess energy you took an earlier to drop back down to your original ground state level. Remember that? With each type of emission? We have a series name involved and these series names are connected to the electromagnetic spectrum where they fall somewhere between UV and the microwave region. The greater the fall from a higher energy state to a lower energy state. The more energy that's released.