 Hello everyone and welcome to tutor terrific today I'm going to be doing a chemistry video for all you high school students out there or early-level college students who are having trouble with electron configuration and orbital notation now Matter of fact, I just wanted you to know that this is actually the first time you guys have worked in quantum mechanics Because we're actually working with the first four determined quantum numbers This is the basis for setting up electron configurations and orbital notations in chemistry Now I just want to make sure you understand that we're talking about the electrons that are orbiting the nucleus of an atom Now these electrons orbit based on quantum mechanics And so there are certain rules and certain exclusions that apply to where they can be and how much energy they have Those restrictions are given by the quantum numbers now not to get too much into it I'm just going to explain the quantum numbers and how it relates to these two concepts And is the principal energy level quantum number and it can take on any of the natural numbers one two three Usually on the periodic table of elements. We only go up to seven. Okay, and those are all radioactive anyway So that's the first number and you need to know what principal energy level you're dealing with next L It's called the angular momentum quantum number now We don't think of it as L and we don't number it as L. We look at it as letters s pdf Now often these are called sublevels in high school chemistry and There's also a G in an H But in high school chemistry, but don't look at those because they're theoretical and then ML the third one It's called the orbital quantum number and we just think of it in high school chemistry as an orbital and Each of the orbitals is given a line depending on which sub level you're in You have a certain number of orbitals Okay, for example each s sub level has one orbital and each p sub level has three each d sub level has five and Each f sub level has seven so We have to keep track of that and I'll show you how that works But an orbital are these given by these lines, okay? These are like houses that the electrons live in then we have MS which stands for the spin quantum number I'm not going to try to discuss what spin is. It's related to magnetism. However It can either be spin up or spin down. Those are the only options for spin Now how do these all come together in electron configurations and orbital notations? I will explain that here with an example of carbon on the periodic table. You know that carbon Has an atomic number of six that means it has six protons and six electrons more importantly in its neutral state so This is what an electron configuration For carbon looks like these large numbers here Relate to N. Okay, the large coefficients to the letters tell you what principal energy level you are in The letters themselves tell you what sub level you are in and then we have down here The orbital notation. I'll just call that oh and for short This is the orbital notation for this electron configuration for carbon You can see that the orbitals are drawn as the lines and then the electrons themselves are drawn given their spin You can see some up arrows and some down arrows and over here. You can see just some up arrows Okay, whoa, there's a lot of information on here. Let me go through it for you What we have to understand is that the electrons as we add electrons Meaning we increase our atomic number. The electrons are always always going to find the configuration Results in the lowest possible energy for each electron. Now a sort of analogy to that is what do we tend to default to? The most lazy position we could possibly be in whether that comes to this work circumstances or being at home or shorts What have you we want to expend the least amount of energy possible? It could directly actually relate that to this concept But the electrons will do that as well and so the filling order is not Super straightforward because of that because these sub levels s p d and f have increasingly higher energies associated with them So let's go through the filling order without looking at this diagram I'll explain this diagram in a second. We will start with the lowest principal energy level, which is one We will fill number one first Here's the thing the first principal energy level only has the s sub level in it Okay, so we will fill one s first then we are completely done with n equals one The principal energy level completely done Next we will begin with the second principal energy level and we will fill that up entirely Number two the principal energy level number two has an s sub level and a p it has an extra sub level p So the principal energy level two has s and p sub levels. They will fill in that order Then we're done with principal energy level two We will go to principal energy level three which has an s sub level a p sub level and a d sub level We will start after two p. We will fill up the s sub level of Principal energy level three then we will go to three p and fill that up now look what happens This is the first sort of anomaly For s what in the world? Why would I not fill 3d next? Well, it turns out 4s is a lower total energy level for those electrons So they will fill 4s first. They will skip 3d and well, they won't skip it. They will postpone filling that Sublevel so we will fill for s and then we will go back and fill the 3d sub level Then principal energy level three is done. We have started level number four right here Then we will continue with level four and we will fill for p Okay, now four actually has s pd and f sub levels But f has such a high overall average energy that it takes forever to get to it in this list I'll go over that after 4p then we skip We postpone filling 4d and we go to the next principal energy level five and we fill its s sub level Then we go back and fill for d Then we will continue with five s and we will not do for f next We will go back to five and fill five p next the next highest energy is 6s and so now we're in the six principal energy level We haven't even finished filling for yet, but that's how it goes 6s is less total energy So we will fill 6s then we will not go back to 5d 4f squeezes in there right in between the two and we fill 4f now Principal energy level four is done now. We will continue trying to finish out five We will we've got five s here five p's done here five d is next we will fill those then we will go and Back to Six and we will fill 6p. That's the next highest one right remember We started six here and it took us to get to here to continue to work on Principal energy level six we will fill the p sub level next then the next We're kind of complete repeat the pattern that started back here At the next level up at 7s will be next We will start principal energy level seven which has all four as well as pd and f But we will never get to d or f in the seventh sub level and we will never get to 6f as Well, so we go to 7s then we fill 5f. We're gonna go all the way back and finish five now Now we've got all of five sub levels done Then we will continue working on six fill d and then we will work on seven p Now when we get to this point down here in these last couple rows everything's radioactive And it's been artificially synthesized on the periodic table when 7p is filled That's actually element 118 which was just recently discovered It has like a half-life of maybe a few microseconds So it's hard to say it actually exists, but it's been named and We're never gonna really be working with those configurations at that high atomic number, but let's Look at over here because this was I'm sure quite confusing to some of you It's like how am I gonna remember all that well There are filling order diagrams ad nauseum on the internet, and I have made one for you here Now what it shows you is a pathway you can follow To fill in the correct order what I've done first is I've written out in columns the principal energy levels and Categorize them by sub level So all the s's 1s through 7s are in the first column then I move over scoot down one because Principal energy at level one doesn't have any other sub levels, but s scoot down here and write 2p through 7p in the next column and Principal energy level two doesn't have a d or an f either then we move to the next row, excuse me column and We're gonna work through 3d through 6d and those are actually used on the periodic table And then the last two that are used on the periodic table are 4f and 5f now as you can see things kind of Look like a triangle on its side a little bit We start to down here. We never get to these and up here these don't exist. So this is a filling order diagram now How do I move through it? I? Draw these diagonal arrows. That's the trick These diagonal arrows you start drawing one through 1s then we Turn around with the little dotted line and go to the next arrow what sends us through 2s See how it's lining up with the order here Then we when we get to the end of this diagonal row we go back And start the next one Then we see we're gonna go through 2p next and then 3s The order is matching then we're at the end of a row we go back to the start of the next one 3p 4s So so far everything's matching and then as you can see 4s We didn't go to 3d after 3p We went to 4s then we come all the way back around and we go through 3d 4p 5s come back around go through Next 4d 5p 6x Then we go back around and go through 4f 5d 6p 7s go back around 5f 6d 7p Directly matching the order you can memorize right there. So this is a super helpful diagram Now most of you in high school will have this diagram provided to you Maybe if you're in college you won't so make sure you understand how I just generated that And go back and watch that again start with drawing the columns out Organized by sublevel Numbers increasing as you go down then draw the arrows diagonally like so Moving down one step at a time Connecting the arrows with little backing track dotted lines to the next tip of the next Next tail of the next error on the way down. Okay. Let's try to use this We will also need to know the following thing how many electrons This is electrons how many electrons are fitting in each sublevel S sublevel is the smallest And it has two spots for electrons P is the next largest it has six spots for electrons D next in line has 10 spots for electrons and f the last one in line has 14 spots for electrons Okay, let's try to make an electron configuration for these examples. Let's start with an easy one carbon If you look on the periodic table, the atomic number of carbon is six again Like I said in the last clip that means it has six electrons. So let's start filling them in We will have to start with 1s How do I write that I can have two electrons in it and they're both in there? I write a little superscript 2 by the sublevel So what I what I've done now is I filled two electrons in the 1s sublevel Next I'm supposed to fill 2s And there are two spots in each s. So I'm going to put a subscript Excuse me a superscript 2 there as well Then it comes time to fill 2p How many electrons have I filled so far? Well, I count and add the superscripts not the main Coefficients the superscripts. I've filled four electrons. How many do I have total to fill six? The next sublevel is p. I have two left to fill. So I'll write 2p 2 Yes, it is not completely full the p sublevel is not completely full and that's just fine So we have 2 4 6 we have the correct number of electrons. We have the correct filling order and we are done All right, let's try a harder one argon argon Has an atomic number of 18 many more electrons going in here So let's begin 1s can fill two in each s 2s Fill two into that one 2p So p can fit six if I add two and two to six I get 10 total So I'm nowhere near the amount I have to fill so I have to fill this p entirely 2p 6 Next in the filling order is 3s Okay, 3s again like all the other s's can have two If you add up all these superscripts now you can see there's 12 Filled in so I need to keep going to 3p Since I filled 12 so far. How many more do I have to put in? 6 to make 18 total Aha, that's exactly how many can fit in To the p sublevel anywhere. So now I have finished argon Next cadmium 48 I'm going to need this entire line to fit this all Okay, 48 electrons So I'm going to go through a large list with you and I'm going to show you how this awkward filling order begins So as you can see we're going to have this entire argon Because it has at least 18 electrons 1s 2 2s 2 2p 6 3s 2 3 p 6 All right now. Let's continue. That's 18 4s 2 Now we have 20. That's the next one I was supposed to fill then if you look at the diagram I go back and fill 3d 3d So I'm at 20 right now If I fill 3d that gets me to 30 because d can have 10. Okay, that's good. Now I have only 18 left What's next after 3d guys? 4p 4p, how many can I fit 6? That would put me up to 36. I still have more to go To get to 48. What's next after 4p? Guys, look you'll see it's 5s 5s can fit too What does that put me up 38 now? I only have 10 left What's after 5s? None other than 4d How many can fit in d 10? How many do I need exactly 10? Because right now at this point if you add up all the subscripts, you'll see I have 38 So I need 48 so I will totally fill that d sub level. Aha. I have finished cadmium So this is an example. I'm going to go over a few quirky ones next before I show you some of the quirky Um elements in the periodic table that fill a little bit differently I first want to show you how you can check your work while you're doing an electron configuration using the periodic table So here's the periodic table without any of the elements put in I just want to show you what's called the blocks of the periodic table that relate to the sub levels s, p, d and f If you're over here in the alkali metals or the alkali earth metals, and that's where your um your element is your last Electron is going into an s sub level. This is what's called the s block now if you um look at the periods period one two three four five six and seven Those are the actual Energy levels of your last electron. So if you're for example at hydrogen right here, you're filling the one s um electron sub level So it's quite helpful in addition. We have the uh over here the transition metal section This is where the d sub levels are filling particularly three four Five and six in each of those rows now. These are where some of the quirks happen But i'll explain that in a minute. So this is called the d block Down below in the what's called the inner transition metals or the rare earth metals these two rows We are filling the four f and five f Sub levels, so that's called the f block And then then this last block over here on the far right This is where the p sub levels the sub levels are being filled This is called the p block and they are being filled like this two three four five Six and seven Okay, these are the blocks now the only one that doesn't follow this pattern is helium Helium is filling its one s Sub level over there. It's hard to place helium and hydrogen as you might already know Also notice that the noble gases over here That is where you will see a p Six like we did for argon in our last clip So let's go over the transition metals that are quirky What do some of these transition metals and actually some of these rare earth metals do? Well, it turns out that both the d And the f sub levels do not like to be partially filled in certain ways They are not stable if they are not half filled Empty or totally filled to the point that sometimes the higher level s sub level that was filled over here Is stolen from quote-unquote to make the d or f sub level halfway or whole filled Instead of filled partially to some other fraction That is overall less energy because it is more stable The transition metals in particular that behave this way are c r for chromium c u for copper m b m o r u r h p d that's palladium palladium is extra weird because palladium steals not only one s but two s's to fill the d sub level silver ag platinum pt a u for gold and d s which is way down here Which is a totally unstable element that was recently discovered. Okay, let's look at two of these examples first chromium and then palladium So since we are in the d block, we are going to chromium is over here and palladium is down here We are going to finish by filling that d sub level now. Let's go over this chromium Will actually steal one s electron from the s sub level before it So let's keep that in mind the filling orders over here. Let's begin 24 electrons so one s2 two s2 two p6 Following the order next would be three s2 And then three p6. How many electrons do we have so far two four 10? 12 18 only six more so four what you would naturally do is do four s2 And then three d. How many left? four So we do 3d4 3d4 Is a very notoriously unstable configuration four electrons in the d sub level So what's going to happen here is that one of these four s electrons will go into the d to make it d5 So now we will have four s1 3d5 Matter of fact, that is more stable than four s2 3d4 almost all elements in that area Um avoid 3d4 and 3d9 in particular So that's chromium now. Let's try palladium 46 total electrons. I'm going to need this entire space So let's begin one s2 two s2 two p6 three s2 three p6 four s2 3d10. Let's just check and see how far we are two four 10 18 28 30 Okay, we have 16 left once after 3d10 four p6 So where are we at now? four 10 18 20 30 36 10 more 10 more so next on the list is five s2 Okay, so that's uh that makes eight more and then we would expect four d8 Here's the problem. This is also unstable 4d8 is not stable Palladium wants it to be a full d sub level so it wants it to be d10 Where's it going to take those electrons from from five s? five s Now has zero electrons in it and we completely erase it And 4d now has 10 electrons in it This is a totally odd one out palladium All the other transition metals at least keep one electron in the next highest level s Sub level. All right guys, I'm going to do one last example for you It's going to be like the major test because it's pb. Does anybody know what pb stands for? lead lead has 82 electrons So this is going to be a long process So we're going to start just as normal and I'll speed through this first part until we get close to 82 This entire section of the Diagram and we ended up at around 6p right now guys. I have 10 20 30 38 48 54 56 70 80 82 I need two more and they're going to go right here. Let is right in the middle of the p-block 6p two Okay, guys Wow Electron configurations when you get used to them They're quite interesting and they're quite fun to do But you have to know the filling order and how many electrons can fit in each sub level So guys what I'm going to do is I'm going to do the orbital notation in a part two video Which you'll see very soon. All right guys. Thank you so much for watching. This is falconator signing out