Lecture 09. Breaking the Octet Rule


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Lecture 09. Breaking the Octet Rule
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Brindley, Amanda
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Chem 1A is the first quarter of General Chemistry and covers the following topics: atomic structure; general properties of the elements; covalent, ionic, and metallic bonding; intermolecular forces; mass relationships. Index of Topics: 0:00:17- Breaking the Octet Rule 0:06:44 Resonance Structures 0:14:28 Delocalized Electrons 0:16:40 Line Structures and Rules 0:24:06 What is the Formula... 0:27:55 Benzene 0:30:30 Electronegativity 0:40:06 Microwaves 0:44:29 Back to Lewis Structures
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but it's not always that we've been talking through a Lewis structures that briefly act out roles just a quick reminder on all the rules that were following as were going through this lecture you can't have more than a
electrons in your 2nd period elements and of course your 1st year right hydrogen helium coming to but when you get to that 2nd period you cannot have more than 2 relied on less than 2 it doesn't happen a lot but it happened a lot with things like beryllium In boron that yield in whatever you do no more than no more than 8 electrons so you can't put 5 bonds on nature dinner car bearing like that and you Centerior elements we talked about when you get down there now we have all these d orbitals you're allowed to using you're allowed to use those in order to form a bond that have more than a electrons told so you're allowed to get hundreds of electrons if need be me and started working through some Lewis structures that had that and showed us that so you have some commonly ones commonly use 131 seeing 1 will have less than 8 allowed thoroughly almost formed to bonds leaving it with 4 electrons aluminum or a lot of times due 3 leaving just 6 valence electrons in Boron does the same thing will oftentimes just have so back to our Lewis structures that we've been kind of working through In class last time it so
we carried on a bunch in Samarra left off with PO the 3 in so remember a 1st step whenever we do these Lewis structures is to ,comma all of our electrons so we need to go through me to say we have 5 from the phosphorus 6 from the oxygen 7 from each clawing so that at the end of all this we know exactly how many we have to deal with and so when we go fairly put this and we start with a central element in this case most of the time it's going to be the first one written something of this sort but sometimes it will be it's also usually the least elected negative elements on this case that follows so we put the phosphorus here and we put all of our other units around it now if you go through when you put in all your electrons in the form of a indirect you'll find something interesting that we didn't find with the other 1 we have a little bit of a choice so we could do this and if we do that everything has not kept so everything is technically happy but if we go little bit further with this now remember we also talked about formal charges and were told you go home and practiced in the formal charges with the other Lewis structures that we drove but now we need to actually do with this 1 because you're going to find something interesting closer do that for oxygen what you'll see is that you have 8 valence electrons in the periodic table but here it owns 7 1 2 3 4 5 6 7 1 from the bottom so that's a negative 1 and if you do it for phosphorus you'll see the phosphorus has 5 from the periodic table In here only owns 4 1 2 3 4 so it has a plus-one so now we have a minus 1 a plus-one charge they're sitting right next to each other and we can do away with those charges so you're always looking to minimize formal charges New jobless structures remember in there and no example we wanted to pick the Lewis structure the lowest formal charges he wanted the same things here so this actually isn't going to be correct what you need to do is you need to form a double bond to the oxygen and then get everything else the architects like you did before and now it you'll see Is that everything not cat except phosphorus Foster's has more than a knockout but that's OK but now all of their formal charges are equal to 0 so that is that's more of a stable and having the structuring have formal charges so this would be a structure next thing more said now it's still left for minus the moving doing some I so similar always 1st step ,comma Paul electrons so we have 7 from the chlorine plus 7 from each fluorine and don't forget that you have to have 1 more because of that you would have a negative charge 1 more electrons added so we get 36 electrons total we apparently still left a negative 1 which is normally listed 1st in our center so we pair chlorine in the Senate and we put everything else around it now if you feel all year Texas is 1 of those places were having ,comma Gillette 1st will keep you from making a silly mistake so far we fill all these it was not everything has an architect of his walk away now you knew when you realize that you're missing for electrons you really only have 30 to here but you had 36 so you have to remember to put those in so now it is liable they go they can go on the flooring fluorine dollar Florida you a bad 8 just meeting that 1 by 1 we can't give soaring more than so it can be that once so we have to put it on the court and so will put it in like put both long pairs on the chlorine now we move on and we'll talk about some others another situation that occurs when you have Lewis structures called residents so what happens with residents in a molecule can have more than 1 Lewis structure and they're all equally stable they're all allowed there's no reason why it should be 1 of the top of the other there's not like when we're talking about a N N O example and we had 3 different there's sort of unequal resident structures he recalled on Thursday including 1 that was most stable this is something a little different insisting that they're all equally stable all just as likely to happen sometimes happens when you can move around electrons not molecules so whenever you're drawing resident structures if you have to take the hydrogen off somewhere and put it someplace else that's no longer really resonant structure you have to just be able to move electrons around which means you can move around Paris and you can move around Bonds and that's it now In reality we're off 3 Lewis structures let stated 3 different resident structures to make up this Lewis structures and technically you do have to have all 3 4 at the crack if I tell you to draw the residents there eventually almost structure for an 0 3 in you only 1 structure technically you're wrong unless I specifically asked to just from once in the risk that the illegality just 1 of those is a real accurate representation of what's happening you have to have all 3 of them because in reality it's a mixture of all 3 so we're gonna go through these 3 examples so that we can kind of look at the different ways that this can be done hurry so the 1st only had
an 0 3 so you're going to go through this exactly like we did before there's really no difference to the so we added by electrons this should actually be out of action so when you go through new right all of this out you put your nitrogen in your son and your oxygen is around now if you couldn't do this and you fill in all the electrons exactly as we did before what you're going to find is that you were sure to electrons and whenever you're sure to electrons that means that you need to go ahead and make a double bond so will make a double bond what is it therefore now it's fill in all of our and so we can do that now a good question may come up and say Well let's look at our formal charges as I can and if we look at the nitrogen this is where I was studying how good a formal charges and we don't have to necessarily writing down all the time so was going to do it out loud so if we look at nature to which they are valence electrons we look at it pier table we have 5 and here we only have 4 1 2 3 4 so we hope plus 1 charge here now if we look at these oxidants we would have sex from the periodic table but each 1 of them has 7 so each 1 of these oxygen is going to have a negative 1 charge so now if you think back to the example that we just didn't just 1 moment go with the BOC all 3 and we a double bond to 6 and I said Well you know hey we have a negative 1 applause wearing next to each other you can fix that making another double bond can we do that here well if you got a new dried out we're going to find is that now nitrogen has 10 electrons in nature not allowed to do that so and this is a case where you can't minimize formal charges stuck with what you have so we're we're going to sleep there navigation to this idea of residence structures that while put the double bonds like you I have taken enjoy it like this instead that the double bond at the bottom left In putter to negative charges here or for that matter why command done it over here and when it comes under there is really no reason I picked the the 1 I did end in reality all these are completely equal In sold to accurately represent this molecule you have to actually draw all of them you can't just leave it as 1 or the other and so if I would ask you to draw the term technically you would have to draw all 3 unless I just ask you to drop 1 now going back to what I mentioned the slide were all these are equal there is no reason why it should have been put on 1 the other so it's not like a N N O example where there was a distinct preferred choice where it had the negative on the most elected negative element in this case were just putting on different oxygen so they're all equally stable we didn't move anything around right we didn't move Adams around we did pick up an adamant catch someplace else we just moved the double bonds in their lone pairs around so we were only moving electrons so all of these are equally stable all of these are allowed and so there's no difference but similarly onto another very similar once we had H C O 2 minor so when we got a draw this 1 we ,comma by electrons and we put our least elector negative element in the center and we drop everything off from so we had to oxygen the hydrogen and so we draw it this way move over splatter double bond but if you go through you is the single bonds you see that you sure in electron 2 electrons the need to make a double bond so I chose to place here but there is no reason why couldn't have chose to put it down here so let's try this out In this puts the minus charge on here so now let's draw the resident structure citizenry say Well why did I put it here as opposed to here there's no reason it's not that it makes it more or less stable it's just weird kind added a quorum so we can draw the other 1 and so both equally stable so both of those earlier need to be there to be completely accurate knowledge think about what I said about having them actually be a mix of the electron are the mix of the structures so what I mean by that is that not 1 of the accurately represents what in reality is happening is this minus charges being shared equally amongst all of them this double bond is being shared equally amongst all of them and so it's real reality a mix of if we are to measure this bond lengths it wouldn't be that 2 of them came out to have a single bond and 1 of them cannot be double bind if we measure really really fast foods that they were all switching no I wouldn't be doing that would actually be in the middle of all of that himself we go back and we look at our next slide we can see some summer
little more what's going on and when we can look at the shakes so if we look at this as sort of a N O 3 and I had all 3 residents structures drawn out here and if we look at this double bonds moving around but actually end up happening is that all of them contribute equally and you end up with a sort of there's there's different ways you can drive but 1 of the ways that will sometimes Trotters would like it .period line going across here what that means is that these elections are you localize they don't belong to any 1 specific place what happens is that all those P orbitals so if we look at this and we think about where people orbitals on what they look like during a bond hearing hearing here and as we move on in Chapter 2 in Chapter surreal have a better idea of exactly how those geometries work but right now we can think about the pure buildings spread over the whole thing in so those are called the localized so electrons there in these sort of areas where you have this residents recalled the localized electron warring visit that also known as we start learning more about how the shapes look at how the geometries look and everything about sort so arms sort of also added something else that helps with homework and things of that sort when we look at the I talked about sort of the bond is being splits between the 3 so if we were to measure these bond lengths when he would actually come out with a back only about 4 words which makes sense because we have 1 2 3 4 bombs being split between 3 different sections 3 different outcomes missiles for bonds divided by 3 is for the birds In the same thing would happen if you were to be able to measure the charges how much of a negative charge those oxygen you would have 1 2 3 are exceeding 1 2 negative slip between 3 adults and so you call about a negative 2 two-thirds charge so that comes up often on your homework OK now I can move on to something that's a little bit off subject but it is not
technically covered in this chapter of your book but it's something that people forget to teach you guys until it's really too late or using them this comes up a lot in organic chemistry and you'll get really really good at an organic chemistry but you need to have a little bit of an idea of how to do them and how to work with them before you get there so I knew that when you see him in a book you know what's going on and it never gets formerly taught at many places here so I would chose to put it in here along with binding 1 room really getting into the structures and what molecules looks like and things of that sort so these Oregon he called line structures so here are the rules were for you but really that's the only way to get that this is to do lots of practice so keep this sorted by you as we're doing this you can follow along with the roles that the reason why we want to have these lines structures in together that makes it really fast festival to drop so they I know women working with pretty small molecules know for 5 different outcomes all combined together but when you start looking at these big that's a different heads of drugs on prescription drugs sings about sort molecules Nigerians really huge molecules and you have to drop every single carbon in every single hydrogen every single mom and that molecule starts to get a little bit tedious of if you know classes you probably seen different hormones and things of that sort and you can imagine having the jobless out its full glory Lewis structure as we've been doing and how much room that would take up in how tiring I would get lined structures says hey we know something about molecules successfully organic once we know how these things act we don't need to draw everything and so whenever you see a corner were you see an end line so will skip ahead at the
interval the 2nd show you still a corner or an end of line that's going to be a part of go ahead and assume signing you have a little corner got too crowded any time you come to the end of the line and there's not some other Adam written there that the Cotton too you assume that carbon is going to have 4 bombs so of carbon has for bonds already can see all those for bonds drawn in you don't really have to do anything without current that's just a current now if you have something like this we look at this problem it only has 1 too OK what that means that it has 2 more bonds someone ,comma likes to have for bonds so hydrogen you can assume that the there we just on drumming so this carbon because it has to bonds here In it needs to more this carbon must have 2 hydrogen attached that we just got to be able to see at the moment and that saves a lot of time we're drawing itself but it so that all your other Adams those have to be drawn into it any figures normals Adams of those have to be drawn into some really the only thing that you're watching out for here is common in the corner of the end of a line in all the figures the attached to the cop there's other than 1 of the biggest thing that comes in when we start talking about hybridization we don't problem Paris so lose structures we always had drawn all along pairs so we always knew as soon as we look at an atom humming along Perez a had in mind structures we don't and that's going to come into play a lot when we start doing via CPR theory and hybridization and things of that sort when we care about what those lone pairs are and whether there are enough in line structures we don't drop so 1st such practices drawing some and then we'll go on to a few more complicated ones that I wouldn't expect you to be able to draw I couldn't do it this way and give you this and have found new driver could just give you a formula and how the drive but I would expect you to be able to tell me the empirical formula will start with this direction I want to hear a moderate help in this way can point to of so if we start this 1 when he got a job these weeper pencil down in which they will back the 1st carbon now so we just put that now now we go up to now we have 1 2 carbons that takes care of those 2 we go down 1 more time said 1 to 3 carbons we have 1 more to go so we do that so now we have 1 2 3 4 carbons and we have 1 2 3 4 so now we have to worry about a and H 2 so we draw a line to good a N H 2 and we drop we don't have to draw on any of the hydrogen and those are all assumed to be there because carbon only has 1 by 1 so we have to assume that has 3 other ones that we just can't see so that's 1 2 3 hydrogen many here 1 2 hydrogen hero 1 2 hydrogen went to hydrogen no notice on the nature and we have to draw those hydrogen then you can assume that the hybrids are a hierarchy a anything other than carbon so we have to go ahead and write pattern so this is how we go about drawing a line structure structures notices nitrogen it also has a long parrot that lone pair that we just aren't seeing so we don't draw that would draw the line structures but you do need to know that it's there on the students on so we had to carbons and then that's bonded to an oxygen so we have 1 to carbon 1 2 comments it would come down To the OH like that you don't have to draw bonding between and hydrogen you can destroy OH so again once you carbons once you carbons and then down to the and then you assume that because this has won bond here must have 3 hydrogen this has to bonds so it must have to hide now moving on to a little bit more complicated 1 now we have this sort of Pentagon structure so sense of common is a corner we just have to draw the Pentagon and then all those hedges we can assume to be there and so we only have to drive oxygen a double bond accident so you can see how this is a lot easier to draw and how that once used it really good at these you look at this and say OK well to bonds there that means I have to hydrogen to bonds here than did to hydrants and so on and so forth so much easier once you get good at it but now this 1 so we have 3 cartons so we can go 1 2 3 so that's 1 2 3 1 2 3 now on that last carbon we have to oxygen is 1 of them is going to be double bonded 1 of them is going to be single bonded and where so against a look at this and say OK we have 1 volunteer here than in 3 hydrogen 2 bonds here so that means we have to have 2 more hydrogen to hydrogen and in this carbon descending hadn't done it because it already has 1 2 3 4 months so here we have 1 2 3 4 bonds if you looked at this you would say OK well I don't have to worry about hydrogen so that's going in that direction notes go in the opposite direction the book
now let's look at this 1 and say OK well how can we figure out the empirical formula for a structure that looks like best so 1st we need to start with something usually the the service ,comma until you being good at these it's also giving it a go ahead and draw everything in but while you're drawing in hydrogen I would drawing yearlong Paris St a so if we start with all of corners we'll have a common right here here here here here hearing here 1 right there there's nothing I was drawn in this is 1 sometimes you'll see them dry and the CH 3 groups sometimes you well so I could just as easily like that a blank enlightened leaders just an end of a line and you would have to notify CDC figures it drawn both ways and then over here received so you can't call them up you have 1 2 3 4 5 6 7 8 9 10 11 :colon see know that it's going to be CIA-led never hated and they're a bit more tricky so if we look at this 1 we have to bonds already it's Oregon need 2 more bombs here we have 1 2 3 4 months and so were upset when I can have any hydrogen that we look here and that's the same thing 1 2 3 4 . 7 0 100 and that so we still just have these 2 now I come up here and we see that we have 3 bonds which means that we must have 1 of the 1 that we can't see that the hydrogen so to hydrogen 100 same thing here 1 2 3 4 we must have another hydrogen same thing here now we look at this 1 and a half hours for bonds and so we know that OK we're all sat so know in hydrogen their structured 2 3 4 5 To off here gives a 6 and 7 and then the 3 pounds here means that there must be 1 more still worked 8 and then 9 10 11 12 13 14 15 so where up to 1500 and so is the 11 aged 50 now for the other Adams use go ahead and they're all drawn out for his factory image so N O since the 11 aged 15 N O 2 and going there and drawing them out the 1st few times is fine them more than recommended now let's look at this so lots of their comments so we know each corner here is going to be a occurrence set in the service sector and this 1 here 7 8 so we have a common support now we consider ceremony a hydrogen is the more difficult 1 of the group to have 1 here and 1 here we will experience here in you can see for both of these they have for bonds are right and no we look here we only have 3 bombs so there's going to be a hydrogen their same thing for 1 the same thing for this they all only had 3 months they all need a 0 2 1 2 3 4 5 we look at this 1 for bonds are this 1 there's too long so we need to move on so 6 7 here we have to balance so we need to move 8 9 and here we have a moderate enough so 10 11 so it's C 8 inch 11 so now we just go through in Karbala so we have a nitrogen and we had to oxidants SO NOT 3 of the 8 H 11 NOT now let's look as sort of an interesting structure just because it's again this is a little it goes along with the other thing that we've been talking about this gets under the P of orbital do localization to and it's a good place to kind of put it and now that we see what the structures look like so this takes this spring these residents structures that we've been drawing in with the line structures wine structures on different you can draw resident structures within just like you can Lewis structures so if we look at the structure this is bending Inc that's just that's just the name you would need know for sure so if you look at each 1 of these each 1 of these corners of their carbon in each 1 would have a hydrogen now there is no reason in this case to draw benzene with this the double bonds here here and here you could equally draw them here here and here and so that means that we have a resident structure between the steel where we can draw the double bond alternation this way or in double bind altering that way here's a drawn-out with the hydrants just so you can see the each 1 would have to have a hydrogen now 1 of the other way that you'll see this drawn because these are all the localized in the are all shared equally remember resident structure really mean that it's somewhere in between that each 1 of these would be one-and-a-half bonds and so sometimes you also see just run like that With a circle so that is it incomes and lots of becomes a lot for applications and it's something to be aware of information exist to see these groups lots of different places and when you get further inorganic you'll start calling aromatics and the vast sort so in this case this gives you a little better picture of how P orbital the localization work in this case over the impairing so the history here and interactive elements to represent Europe you were so 1 lobe of the pure and all the other lobe of the plural and Puel's are forming those double bonds that 2nd bonds each 1 and so you get this big green of water and that's how this looks so this is sort of a resident structure that shows you the pure overload the localization over the entire thing you can now kind of imagine the annual 3 looking the exact same way now we're going to do a little bit of more talking about elected negativity we resources already talked about the 2 friends before now really get into it all the more and talk about Paula bonds and things of that sort of little more intensely than but we did before before we just sort of talk about it as this tendency of an electron to share still Augustus to take more of the electron density away from its bonding and that was really all we talked about we talked about the trends so we talked about as you go across the periodic table this way we are increasing our election negativity something like fluorine and oxygen and nitrogen are extremely elected negative things over here on we talked about how as we go up the periodic table we had increased Lecter negativity which means of Florence very Elektra negative things down here so now only talk a little about more how this applies to actual chemistry so remember if
in this case there's not a lot of exceptions right now was 1 of the nice things about electric utility when he took the exam on that resonated in all the exceptions and that's because they already have a stable architect look at the briefing not that there is stable a invigoration so because of that we got this nice and the smooth flow of all the way up following the trend with just a few exceptions that we don't worry about too much now let's talk about how this selector negativity in Howard the differences in the electric utility between 2 elements are bonded to each other and their effect properties of molecules so polarity is something that we have put may have heard of in this workers of polar molecules or pull the bond occurs when 2 elements that had very different electric utilities are bonded to each other so if we look back here if we have something on the side of the periodic table bonded to something over here where there is there is a difference in Electra negativity the women they're going to be stealing all the electron density 20 cells and so if he is an element has more electric density being pulled forward it's going to have a positive turn judge well more electron density electron the negatively charged so it's going to be a bit more negative than positive so if you take
something like H afterward HLI and you look at their electric utilities you can see that there's a difference between them and because of that the electron density isn't shared equal in this case hundreds were electrocuted so steals away from the lithium giving it is unequal distribution in something like that you have this hydrogen history on equally and so now the flooring has and little bit of a negative charge on something like I 3 would-be non-color III has just died the organ harvesting electrocuted they're all being know spaced out equally so they're all Sharia completely equally there's no difference in authorizing the play here and here there would be now this gets into the idea that there is agreement between straight if we
share something here in here let's say OK without the Polar it's not sharing equally this would still more of the electron density than that but it's not quite the same thing as you take something like this hand bond it was something over here has a very very low Elektra negative so there a difference in the differences electric utility United we have small differences big difference and so that's what this is
getting into if there isn't just a ridiculously tiny amount of different electric utility or they're exactly the same it's not going to be a polar if you have a seat at the head of molecules to molecules achieving 2 Adams bonded together and their differences a little is left open 2 so there is a difference but it's not that big of a difference then it's going to be a polar covalent bond now it could become greater than 2 that's what we did in the fact that now is basically stealing the whole electron or more worth electron density and that becomes an ionic bonds so this gets this statistics the original definition of the difference between our in polar covalent urging Kinkel bill before we talked about it being a metal and non-metal a metal not we talked about covalent being all my medals and now we can kind of see what if you have things over here they're are all about you others the relatively similar in a lot is assumed to be different and so they're going to be cold real maybe the political aligned but they're still going equally if you take something from the cited period table and something from this side of the periodic table that was issued to difference between the 2 and so now this ceiling so much electron density over to the side that you're getting more of an ironic situation so if
we put that in a little bit more concrete terms don't trend that has left its nucleus poll on the electrons farther away or elect negative are electronic so something like fluorine taking something from potassium it's such a large difference that it's not intake basically the whole electrons worse this is how we can decide on something called ionic character so now it's not as simple as just covalent or ionic now we have the greedy and that I sort of referred to often on the report so if we look at something like Keith yelling I we want no well which 1 it has more on character we can look at the case would can look at the CIA it we can look at the case we can look at the eye now we should do this will probably without having the numbers in front of us as well but I would put them here to see imposing numbers on it as well so we have potassium and chlorine which has you know at a fairly large difference and we have potassium and iodide which also is a fairly large difference but not quite as much so because minus Eriksson because the is so much more reluctant negative thinking I and II Casillas than have moronic character the difference in electronic unity between here and here is more than the difference in electric utility between here and here it's OK and I a share those electrons just a little bit more evenly where K in Seattle the seals them entirely the bully hearing take away more of the electron density because it's more and soak ACL has a greater difference in alternative the key in the CL pulling on those electrons more it's making that bond more and here's a sort of graphic paragraphs this outstanding conceal little that too so here we have lot negativity difference so that's if we take something from you here in here in the subtract the 2 values are looking negativity different and we have cent III character soon can measure how well how much those are ionic or mortgages covalent or not at all and so we get the sort of the sort line where the greater the electric utility difference the higher the ionic character feel there's if you like a little all liars and investors for the most part as follows the score and so if you want to know how old I how much I have on character something has you look at the electric utility differences the bigger the difference the more ionic character so there is no exceptions to this idea with polar it from being a difference of Electra negativity and there is 1 example that sort of epitomizes this as kind of interesting so we have all 3 so this is this is a weird example now With all 3 you could kind of single that's going to be like I write as the I 3 minus all of them have the same electric utility and so there's not going to be any sort of polar issue here not quite it's not quite how it works so if you got the Lewis structure for the here just have the wine structure dropped so I don't have any long pairs but if you're out of the lone pairs here so ,comma how many electrons 0 3 hours then where my missing so need to long Paris here 3 here in 1 somewhere else the end accident and we kind geometry too much but didn't can see that a there's a lone pair here that's long Paris and pick up some room and saw that 1 pair the kind of push destruction now if you look at at how these electrons are distributed notices formal charges here there's nothing we can do to fix that we can't put a double bond here to fix it like we did with the appeal still 3 examples energy look at it keeping in mind that there is a long pair here why couldn't we put a lot like and we put this Bond here it's been a great track Cabral right if we had 2 4 6 8 10 electron accidents not allowed to do that idea second-period elements so we're stuck with this sort of distribution of electrons which means that if you look at those residents structure is going to be a Delta positive in the Delta negative on it in Seoul it's kind of weird situation where you have 3 items that are identical they're all oxygen so they all have the exact same Elektra negativity but the distribution of electrons set up so that they're going to actually be Paul it does have a dipole is the polar and so will get more into the details of the geometry more into the details of how you know of anonymous polar but it is interesting to note that there some exceptions to on some odd situations that you need to kind of keep in mind it's not always quite as simple as just looking at the differences electronic utilities would have to look at geometries and things but so before we don't use some more examples of looking at polar bonds and things of that sort I thought there's some some interesting applications as her combined the 2 things that we learned Chapter 1 and invest so if we take a and I show you some of these and if we have something like Michael it's so we know what microwaves are now we have an idea of what microwaves are now we know that they're just electromagnetic radiation and this electromagnetic radiation and electromagnetic radiation has wavelengths and we know that the only thing that really makes my its specialist is important in that particular region of the electromagnetic spectrum and so it for an hour particularly developed magnetic spectrum what happens is that these microwaves are able to actually go ahead and its sights I water molecules so when you likely something when you're really doing is you're taking water molecules in your moving them around and so there this little demo from the fat website which I think I've shown you before where if we turn microwave on those in waves admitted taking they're going bounce water molecules around so you turn microwave you have water molecules moving around and all the other bumping into each other rubbing against each other and when things do that what is that make construction right if you have friction between things you say USC Virginia hands what happened on that warm so the same thing happened here you use microwaves things will inviting Chapter 1 in microwaves excite polar molecules impact so they'd say polar molecules so Water is going to be polar rightly oxygen which is really a elect negative we hydrogen which isn't super electronic have more than you would think for a period table but on society .period and so definitely polar molecules so the microwaves can excite those bouncing around and except the food now my can you put metal with why would that make any difference well it's not necessarily that you can't put metal a microwave it's that you have to worry about this it
doesn't necessarily related to this but it is it is an an interesting little concept so that I can put my own electorate is just that if you do if you put container have big heavy container in a microwave it's got block of
electromagnetic radiation it's going to take it it's going to stop all the microwaves getting into the water and so the water can speed up and then therefore your food can heat because the metal bounces electromagnetic radiation microwaves back at everything thing now that's really real mettle heavy-metal a big big bowls of metal things that sort here tinfoil at the small things of metal into a microwave then you may have noticed that suddenly struggling sparks and that's just because now you're kind of exciting the electrons around
so this actually shows you how you can do in a very controlled
manner so if you have a microwave In
the name of a light bulbs sold almost always good in the sense that it had metal in it so shows you happen to be put metal and yet it's also very controls its inner atmosphere so it's not the number is not the spark but yeah well lighted up so you can see that OK it's really just that you bring your your bring Mallory you're sending a literacy through metal by heating it up as shows you that Hey you can do it if you had and the atmosphere is normally you get something you get the spots because the metal of the electron there's going through them this kind of cool the elections you that so that the whole different phenomenon the weight of the water works so they're not necessarily related on it
so I go back to those Lewis structures Lewis structures I've told you were going to keep out pretty much the entire time over time and ridiculous Oregon and decide with bonds the polar now be careful here were not deciding which molecules are polar were deciding which ones have Paula bonds we can really get into the idea of polar molecules quite yet you just don't mean we haven't quite cover that material but we can't alter not only can say OK which bombed the pole somewhere in the back through all of them and decide that the
filing said after the meeting In the 2nd to adjust so if we look at into it so this is kind of a nice example of her off with a we have nitrogen bonded to a maintenance so there's not going to be any difference in electric utility they're they're all going to be the exact same so this 1 is going to have no polar bonds now moving on to the next 1 if we have carbon hydrogen oxygen so world and carbonated not shouldn't so this lonely and drawn out like this we decided this was the proper so the proper withdrawing it because the winter formal charges work and because of how a architect work now if we look at this which won the pole adhere to deal with a current hydrants there's a very very very tiny difference in electric utility it's such a small difference that we don't consider that a Paula bond but now between carbon oxygen if you look at those that's definitely Paula so the sun has Paula bonds and again we're just deciding the bonds of polar were not deciding if the molecule itself a sport or not quite there yet we have to use India CPR theory 1st now we look at X after 4 4 plus this 1 we have a noble gas inside so noble gasses are definitely not very elect a negative and we have all these fluorine Florida definitely very elected negative so all bond the Paula so that was just ordinary people and then will come back and will decide which 1 of these on have polar molecules here if you ask the analysis look at a N O 2 of to this will there are very complicated exemplary right where we had to go through we had to draw all these different what we're not calling resonance structures were removed the electrons around but this resident structure was different than the other ones because these were unequal trade the other ones were all equally shared and so those a resident structures that you had to draw all of them this 1 you had just have to draw the most stable because this 1 is better than these so were just looking at the we say Well which 1 of these have Paula problems With this bond has a formal charge that makes it a little bit but will it not to pay too much attention to that 1 and let's look at this bond of this bond is definitely polar women nitrogen and oxygen we haven't made a formal charge here positive formal charge here is this one's going to definitely be people but now will get 6 as soon will consist sexily look at the differences and polarities where they are it we know nitrogen and oxygen are flooring the super elected they all fall on section of the periodic table with a very very highly automated sulfur and not so much it's sort of more in between in so every 1 of these other people now you'll also going through the use in this all
happened throughout the rest of the quarter something they do skip certain Lewis structures for certain applications has just because of the completely applied extra complications they don't want you worry about too much so if you notice that were skipping if you want just don't worry about despite a stick them on purpose on a snowy this 1 this is very similar to the 1 we did right now exceed half the only difference is another 1 we didn't have these lone pairs and that's going matter later on when we talk about geometries ending of Aceh but now and we're just looking a polar balance that's exactly before theory not Paula Erickson a very not elected and very elected and so on the public now we had each stress force and so again elect a negative elements we do not election again elements so all of our bond the poll now for the most part and there are substances that for the most part you need to be able to decide whether these areas polar mother Paula Boland there not just by looking at them you don't want to have to be going to the periodic table all the time to make this decision of originally appeared table with actual numbers I always have a periodic table in front of you but you don't want to have to constantly go to the ones the numbers so when you're doing your homework with very few exceptions you shouldn't really be looking at that periodic table ahead in that had all the numbers on it you should be just looking at a normal care table like you know just normal that we have around in deciding OK based on where they are in the periodic table which 1 going to be more polar area which ones can be more native what are the differences how closely they have far where they and decide you're on polarity based on that so now we have appealed and so if we look at this we can decide case are the abound :colon well oxygen that's 1 of our 3 really Australia islands chlorine the halogen so those are very Elektra negative posture is not so much trade third-period says not super far appeared table you know group oversold not very likely negative he said these are ordinary people but I the CLF for minor so that I may or may not be a little tough you it depending so a lot of the Singaporean foreigners both being really elect negative but there is still a pretty big difference between the flooring is still going to be a lot more reluctant quite so even tho we are comparing to pretty highly Elektra negative elements floral still wins Florian still gets to steal more of the electron density and so all bond the polar here too so this is sort of 1 where they're both very electrocuted but they're still going to be all poor so that cases of her Lewis structures and
I think will end there for the day In the next class will finish up Chapter Two and start going in this Andean theory and deciding how we look at these molecules actual geometry as opposed to just and to add to the Lewis structure


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