this is another part of my series where I help youtuber Melissa Lucy Kenton a and chemistry this semester now before we begin make sure to download your free study plan which includes different videos and resources that I personally recommend to help you get you this semester the link is in the description box alright let's begin I'm gonna bring back just the electron configuration that we had before with iron which we found previously so I were to write this out iron would have been 1s2 2s2 2p6 3s2 3p6 4s2 and 3d6 so with ions remember ions are just telling us that it's an element that has a charge so this two plus charge is going to change the electron configuration and I want you to think of electrons and we know that they're negatively charged so if we were to have a positive charge it's actually going to remove electrons and then the opposite if there's a negative charge like sulphur in this case that's actually going to gain electrons so we're gonna add more electrons okay yeah so I'll say here just to note positive charge you're actually going to subtract electrons and then negative charge you're going to add electrons so for iron if I were to just rewrite everything here again where we're going to remove the electrons so we're removing two electrons the place we want to remove it from is always going to be towards the end now this is gonna be really important to know where we're going to remove the electrons from we're not gonna remove electrons from let's say the 3d level because that's already higher in energy versus something that's like 4s D so like vs the s you know I'm looking at the s subshell and I'm comparing the D I sub sublevel sorry s sublevel D sublevel I know that the D sublevel hath more as higher energy than the s so that's why I'm not gonna take it away from there that make sense kind of I just always thought that like the energy levels went an order based on the number no it's based on like they whether there's more complicated than that so it I know I know it's it starts off yes like let's say if I were to compare I'm like the two the two P and the 4s the 4s would have a higher energy level because it's far greater than like you know since four is far greater than two right that's what I was thinking but once we get to this portion like towards the end like those are kind of like similar but what's gonna make it is just the fact that this is at the d subshell there's t sub level and then that's gonna be a little bit more so the d sub level prefers to be either half full so remember D needs to be or the maximum is 10 electrons so half full half full would be 5 so it prefers to either be in this range between five to ten anything lower than that and it's not stable okay so that's why I would actually completely remove this portion and our new election configuration would have actually been this whole thing just - that 4s - okay so I would literally get rid of this and this is this is my electron configuration for this ion okay all right same thing goes for the next one what would I do if I'm now removing three electrons so I'll still do the same thing where I know okay well I can remove it from this 4s you know level so that's gone but I still have one more electron that I need to remove where do I take it from now I can take it from this level and that's still going to be half full like this would subtract one and now we're gonna get five and it's still half full since it wants to be you know either five and up and it's still stable it's still fine so our actual electron configuration would have been this making sense yeah okay and we'll do this for sulfur so I'm just going to write out what sulfur would have been just in its typical state here done okay and then now that we have a negative charge we know that we're actually going to add electrons so we're adding two electrons and then now in this case the last the last like portion here of that electron configuration that's gonna want more electrons because it's not completely full and we know like P to be completely full that's gonna be an S sorry that's gonna mean s it's gonna be at six that make sense yes okay I'll say it again and I'm adding two electrons so I'm adding two electrons to the end and then the maximum amount of electrons that P can hold is six okay so it'll be stable at six so that's what we would want to do so what if that was already six it wouldn't work trick question I wouldn't be surprised if it says like none of the above you know yeah not possible we're not allowed to go past the maximum amount of electrons cool awesome then that's basically the main things for ions now these are exceptions so there are always exceptions to the rules of course these are the ones I'd say to definitely know the first to chromium and copper are probably the most common trick questions I have seen on electric configuration so you may be asked like hey write the configure the electron configuration of chromium and you would expect it to be this but that would be wrong and the reason for that it's it's more complicated I would say it's nothing that you necessarily have to know for this class the actual electron configurations are found experimentally like I said I don't expect you to even know any of that don't worry about that but just knowing what the exceptions are that's important so these are basically the majority of the ones that I've seen but like I said these two most common ones okay so if you're going to know any of these no those first two that the actual ones are these okay so memorize the actual ones do you think yes okay cool I mean another little thing to kind of like explain why is still going with the same concept that like this isn't this is actually not half full right remember we wanted it to either be D 5 or D 10 or something in between and because this is 4 that's why it's not gonna be stable and it moves it takes one electron from this and it grows it goes up to five and then the same thing here like oh this is so close to being completely full so it's gonna take one electron here and now it's stable okay yeah that that's the reason behind these really but there's more don't worry about it yeah that's just weird cuz it's like well then you can fill this all the way right right right but but we look we want to fill the highest energy orbital first you're not first sorry last but we want the highest energy orbital to be half full or full okay so you're saying because the 3 is before the 4 no because of the deep sublevel so the D sublevel is going to be higher in comparison to 4s and if I were to go back here for s 3 D they seem like they're almost exactly the same I'm gonna move them up just a tiny bit just so you could actually tell but 3 is actually higher up in energy like quite a little bit from 4s okay that's why okay alright last thing so we could also determine the overall core electrons and valence electrons just by looking at the electron configuration and as you can tell I already highlighted everything the way we can do this for valence electrons and you should have gone over what valence electrons are but I'll go over it that just means that they're the outermost electrons like like think of the atom like your if your nucleus and like everything that's in there actually let's just not go to biology let's just say our protons let's say our atom is their protons neutrons right that's what's in the middle and then it's surrounded by electrons right on these orbitals so your outermost shell is is basically this like that's where your valence electrons or so that's that's just what it's meant knowing that definition can be important does that relate to like the electrons having to fill the inner shell first or like it's not the same thing before they keep it a bit bright outside okay yeah it's a little bit different I'd say it's more on just like putting a label to what which ones you know do different things valence electrons are going to come back in a later chapter and like will actually be drawing the structures and like what molecules actually like look like on a 2d level and we'll be using valence electrons for that but for now it's just like okay we have these two different things they're used for different like they're used for forming different compounds or forming different molecules so don't worry too much about it right now we will go into more detail and the next few chapters okay yeah but for now just knowing that they're on the outermost shell that's what's important how we find them looking at the electron figure raishin is by this way so we're gonna look at the actual like n value or integer so for and we look at the highest so we're gonna look at the highest end value which in this case is 4 and then we're gonna add though those electrons together and that's where I got 4 so like if we had only I don't know 5s - and that was the highest then my only valence electrons would have been - what do you mean the highest like because 4 is the highest yes oh ok ok I see yeah and then like like if this were a 3 then the valence electrons would have been fine okay I see I see so um okay yeah that makes sense so if the highest was like the 3 then we would count up the electrons of all the threes yes everything and then everything remaining would then be the core electrons that's just what's inside okay in the next video we're gonna go over several practice problems so be ready to try those out