 I will write down the heading here in case of in case of multi cyclic compound in case of multi cyclic compound. So, if the compound has more than one ring present in the compound. So, in this case we only count the number of the peripheral pi electrons. So, we only count we only count the peripheral pi electrons. So, what is peripheral pi electrons I will tell you. Suppose I will take an example of naphthalene, this is an example of naphthalene or we can also draw the resonating structure of this one which is nothing but. So, we will always try to take that resonating structure in which the maximum number of pi electron present in the peripheral thing. What is peripheral means? Peripheral means this thing you start from any carbon atom and you are going along the boundary of the compounds like this along the boundary of the compounds. So, this pi bond we are not counting and we always try to draw maximum possible number of pi electrons along this boundary. So, that is why I have drawn this resonating structure. So, here you see the number of pi electrons are 1 2 3 4 5. So, we have 10 pi electrons 10 pi electrons is aromatic for n is equals to 2. So, this compound which is naphthalene the name of this compound is naphthalene it is aromatic. So, we will see few more examples and we will see the application of this how do we count the peripheral pi electrons. So, these are the examples we are going to discuss. So, how many pi electrons we have here 1 2 3 4 5. So, 10 pi electrons. So, it follows Huckel's rule aromatic integer. Here you see 2 4 6 8 10 12. So, it has 12 pi electrons. So, with 12 pi electrons what we can say with 12 pi electrons we can say that it is anti aromatic because it has 4 n pi electrons following right. So, it is anti aromatic integer. Now, in this one why I forgot to write down the double bond this should be. So, how many pi electrons are there 2 4 6 8 8 pi electrons this also follows anti aromatic compounds. Here you see this carbon this is the non peripheral pi electrons. So, we call it as non peripheral pi electrons we will not count this. So, 1 2 3 4 5 6 7. So, 14 pi electrons it has. So, it is aromatic in nature for n is equals to 3. This carbon atom you see these 2 are sp 3 hybridized carbon sp 3 hybridized carbon it is like this listen to me carefully over here. When we have a multi cyclic system and any of the carbon atom is sp 3 hybridized then what we will do we will see the smaller ring on from that. So, we have 2 rings here if you try to you know understand here we have 2 rings 1 is cyclo butadiene you can say and other 1 is this benzene ring. So, since this 2 carbon atom is sp 3 hybridized. So, it is non planner right it should be non aromatic but in case of multi cyclic ring what we do we first if you are getting non aromatic then we check the smaller ring. If it is non aromatic then we further check the smaller ring till we get the aromatic compounds. But here we have only 2 rings possible. So, the first the larger ring is this the whole ring is this larger ring is this which is non aromatic. So, we will check the smaller ring smaller ring is what then we have this benzene ring first the large ring is the whole compound and then the smaller ring is what the benzene ring which is aromatic in nature. Hence, this molecule is aromatic compound with 6 pi electron we will see some more examples on this then you will understand how to do this. Just you have to keep in mind that we will keep on looking at the ring a smaller smaller smaller ring till we get the aromatic or aromatic ring. This thing we only do when we have non aromatic compound the larger ring is non aromatic. So, we will keep on checking the smaller rings one by one. So, like you see for few more examples if I write down here this molecule this molecule you see it is sp hybridized carbon right sp3 these are sp3. So, the larger molecule is non aromatic then we check the smaller one smaller one is what this is the smaller ring we have right and this smaller ring see the smaller ring of this will be what cyclohexene cyclohexene large is this whole ring the smaller of this will be this cyclohexene which also has sp3. So, this is also non aromatic then we further check the smaller ring which is nothing but cyclobutadiene cyclobutadiene and this ring is what it has 4 pi electron and hence it is anti aromatic the whole compound is anti aromatic in nature anti aromatic in nature with 4 pi electron that is how we check we will see some more examples. So, how many peripheral pi electrons 1 2 3 4 5 6 7. So, 14 pi electrons so 14 pi electrons is aromatic in nature. Another example you see I am giving you some miscellaneous example mixed all these concepts we have. So, if this molecule goes under any reaction so you see first of all if this pi electron shift over here then we will get the negative charge on this carbon atom. So, that will be this C H 2 positive lone pair with negative charge. Now, this molecule is having 6 pi electron 2 4 6 and hence it is aromatic in nature. So, the product will get according to this shifting of electron if it shifts here sorry if it shifts here then we will have positive charge here. Sorry one thing I made a mistake I am sorry this pi electron should shift here then we will get this negative charge here and then we will get aromatic. If this pi electron shifts here then here we have the positive sign then this ring has 4 pi electrons. So, 4 pi electrons means what it is anti aromatic. So, according to that we will not get the major product understood. Now, one more example you see this is the two compounds I have drawn suppose this bond is alpha and this bond is beta. What we have to compare the bond order of alpha and bond order of beta the bond length of alpha and bond length of beta the bond strength of alpha and the bond strength of beta all these three things we have to compare. Now, you see there are two possibility here there are two possibilities one is what if this pi electron shifts here then what happens? If the pi electron shifts here this is the compound we get and what happens if the pi electron shifts here like both way if it shifts gives you the same product. So, the product here it will be we have positive sign negative and positive with a lone pair with a lone pair. Now, with this shifting what happens you see this ring the larger ring here it is aromatic 6 pi electron and this ring has 2 pi electron right this is also aromatic. So, whole compound is what it is aromatic in nature. So, this is for the smaller ring now here you see this ring has 2 plus 2 4 pi electron. So, this is anti aromatic, but this ring has 2 pi electron. So, it is aromatic right. So, with this shifting one part is anti aromatic other one is aromatic and here both are aromatic. So, if you compare the shifting of this from here to here and here to here this is more likely to happen comparatively because we are going towards aromaticity complete aromaticity right it means what this molecule will exist in this form more where the bond order of alpha is 1 right we are comparing this 2. So, this is more stable aromaticity because of aromaticity. So, bond order is 1 here since half part is anti aromatic. So, this conversion is slightly less that and then see for this molecule to convert into this is slightly less in comparison to this one. So, here the bond order of beta will be slightly more than 1 right. So, what we can say the bond order of beta is more than to that of alpha and when the bond order is more bond strength is also more and when bond strength is more bond length should be less. So, this is the order of these 3 parameters we have with respect to these 2 examples always remember one thing this is the comparative study we are doing on we are doing this right comparative study of these 2 molecule bond order of this bond and this bond we are doing according to the aromatic behavior. So, this is it for the no aromatic compounds many examples we have seen you have to keep these examples in mind because all these are important what factor we are applying when and what we do when we have multi cyclic system with non aromaticity or sp3 hybridized carbon then we will check for the smaller ring then smaller ring and then smaller ring till we get aromaticity or anti aromaticity. So, when we have this kind of molecule you must remember what is the method we have to apply to conclude where the compound is aromatic or anti aromatic we will see some examples some reactions of organic chemistry also which involves aromaticity that we will see here next trends before going into the reactions we will also see here aromaticity in annulins. These are what annulins are annulins are these are cyclic conjugated cyclic conjugated hydrocarbon cyclic conjugated hydrocarbon. For example, the simplest one if I write which is cyclobutadiene right cyclic conjugated hydrocarbon the name of this compound is annulin and in this bracket we will write down the number which is equals to the number of carbon atom in the ring. So, 4 carbon atom so we have 4 over there if you write down benzene benzene is also a type of annulin the another name of benzene will be what according to this nomenclature annulin 6 because we have 6 carbon atom present in the ring. One more example you see cyclic conjugated system the name of this compound is annulin 8 since we have 8 carbon atom present here. So, in all these molecule if you calculate the number of pi electrons here we have 4 pi electrons. So, 4 pi electrons is what it is anti aromatic 4 pi electrons anti aromatic here we have 6 pi electron 6 pi electron is aromatic here we have 2 4 6 8 8 pi electrons. So, this is anti aromatic now some more examples will see here this molecule if you calculate the number of pi electrons 1 2 3 4 5 10 pi electrons. So, 10 pi electrons according to Huckel's rule it follows Huckel's rule n is equals to 2. So, it should be aromatic right. So, according to Huckel's rule it is aromatic in nature, but the actual you know the thing is it is not aromatic, but it is non aromatic in nature right and why it is non aromatic because of this hydrogen hydrogen repulsion here. This hydrogen and this hydrogen here we do not have that much space so that it can accommodate 2 hydrogen atom here right sp to sp to hybridize. So, this will be in the same plane then the repulsion between this hydrogen atom will be more and hence to minimize this repulsion one of this ring will come out of the plane and that is how the molecule becomes non planner and non planner molecule is always non aromatic because for aromatic and anti aromatic team the condition is what it is cyclic planner conjugated system. So, it is non planner so non planner becomes non aromatic. Now, you see this example also if I write down in this way and with this bond suppose we have oxygen attached with these two bonds here right with this carbon this carbon and this carbon is attached with oxygen in this plane. So, we have this ring in one plane and with this two carbon oxygen is attached like this coming out of the plane. So, this becomes what when this oxygen is attached out of the plane. So, this ring becomes planner we have a double bond like this. So, this ring becomes planner and planner contains 2 4 6 10 electrons 10 pi electrons this is what aromatic in nature since it follows Huckel's rule right. So, the similar way if you discuss this also if you discuss this also it is also according to the Huckel's according to the anti aromaticity rule that you have this should also be anti aromatic in nature I forgot to discuss this here what happens since we have 8 carbon atoms here. So, this molecule also changes its plane and becomes non planner how it becomes non planner just the structure of this molecule is something like this it is something like this and we have alternate double bond 1 2 3 and 4 right, but this molecule this one is in different plane this one is in different plane that is why this molecule is also non aromatic in nature non planner non aromatic. So, aniline 8 is non aromatic it is not anti aromatic however it contains 8 pi electron right non planner another molecule you see benzene benzene you see it has 6 pi electrons and this is aromatic in nature this triple bond is forms because of hybrid orbital here we have hybrid orbital which overlaps and forms this triple bond here. So, this one bond we are not counting here. So, it contains 6 pi electrons aromatic in nature one more example I will write down this molecule see it has how many pi electrons again you see like this triple bond one of this double bond will not count. So, we have 2 double bond here 1 pi bond. So, we have 2 pi bonds here 1 pi bond will not count. So, we have 1 2 3 4 5 6. So, we have 12 pi electrons here going to this we have 12 pi electrons. So, it should be what anti aromatic, but the actual result it is not anti aromatic, but it is non aromatic in nature why because the molecule has more than 7 atoms present here and it is changes its plane becomes non aromatic right the same thing we have here also non aromatic. So, this is how few examples we have discussed which is important see the aromatic compounds are actually a highly stable compounds. So, you see the stability order I have also written this again I am writing it down aromatic compounds are highly stable because of conjugation and planetarity the molecule gets extra stability. So, this is aromatic compounds and then non aromatic compounds are the next stable compound we have non aromatic compounds are actually the simple compounds which is there at the room temperature. So, that is why the stability order is aromatic non aromatic and then the last we have anti aromatic anti aromatic compounds are highly unstable since it has 2 unpaired electron present in the molecular orbital. That is why the order is this this order is very important they have asked many times this question directly also and the application of this also. So, must remember this order. So, these are the few examples we have discussed regarding aromaticity anti aromaticity and non aromaticity we have also learned that how to assign aromatic and anti aromatic compounds how do we check what we have to think and these examples that we have discussed if you remember these examples in mind if you keep on revising this you will not get any further questions from this all these examples if you remember you can solve all the question that you get in the exam. So, coming session we are going to discuss the reactions which involves aromaticity. Thank you.