 Right on next aromaticity, right on in the property of aromaticity it is a property of cyclic planar conjugated compound. It is a property of cyclic planar conjugated compound right, highly stable because of aromaticity the stability increases. Conditions are what the molecule must be cyclic planar conjugated and it must have 4n plus 2 pi electrons where n is any number 0, 1, 2 and so on. This is nothing but Huckel's rule we have discussed. We have one more property of the molecule that is anti aromaticity. All conditions are same only the number of pi electron is different here. It must be cyclic planar conjugated has 4n pi electrons, 4n pi electrons. The third property we have for non aromatic compound, non aromatic it is made or may not be cyclic. The compound is cyclic when it is non conjugated, non cyclic compounds are non aromatic. If it is cyclic then conjugation is not there it is non aromatic compound. Example of aromatic compounds are benzene ring. This is also an aromatic compound positive charge here. Anti aromatic compound is this cyclic conjugated 4n pi electron. It is also anti aromatic compound. Non aromatic compounds may be non cyclic like this or if it is cyclic then conjugation won't be there. There is no conjugation in this. See these are the conditions we have for these three kind of compounds but there are many examples we will see into this like the theory is not much only this thing cyclic planar conjugated 4n plus 2 pi electron. In different different molecules like mainly the properties are this but there are some other molecules also. Sir what is the square compound? What? There is a square compound. Only square, there is a cyclic square with 2 pi bond. Square with 2 pi bond. Square with 2 pi bond, this one? Yeah. Anti aromatic. No but what is it? What is it called? This one is cyclo-peated ion. Okay I'll write down some examples you see tell me the aromatic mixture one thing I'll write down here stability order of aromatic compound is max then we have non aromatic and the last one we have anti aromatic stability order is this. I'll write down some examples here. Yes. No. See what about this one aromatic or non aromatic? Why not aromatic? Because this carbon is sp3 hybridized no conjugation it is non aromatic. Cyclic compound, no conjugation, non-aromatics. Okay? Now this one, in this we have conjugation, right? And number of pi electron is what? 2, 4, 6. It has 6 pi electron, cyclic conjugated system that is aromatic in it. Okay? Okay? This lone pair forms a pi bond, no? Every lone pair forms a pi bond. Yes, because of this lone pair only it is in conjugation. Pi, sigma, lone pair, pi, sigma, lone pair. Okay? Wait, sir, but can there be a point where like all three, like there are... See, this forms a pi bond. When you draw the structure it goes like this. This converts into a pi bond and this also may convert into a pi bond. That's why all these lone pair will come. Okay? So, 6 pi electron, aromatic. How many pi electrons we have here? We have 2 pi electrons. Oh! Because this is positive charge. Only 2 pi electron here. It is also aromatic for n is equals to 0. How many pi electron here? 2, 4, and 6. 6 pi electron, I mean aromatic. What about this one? Non-aromatic. This one is also expensive. See, when you have odd electron molecule, 5 electron here, 2, 4, and 5, it is non-aromatic. Odd electron is non-aromatic. Okay? Molecular orbital does not form in this thing. Okay? How many pi electron in this we have? You have 4, 7, 8. So you have 8, 7, 8, 9, 9, 10. So you have 10, 10. How many pi electrons? 10. 10. 10. 2, 4, 6, 8, and 10. Okay? It has 8 pi electron. And it is 10. Sir, but the oxygen has... Oxygen has 2 lone pairs, but it is not only one. Sir, why do you think so? Why do you think so? Wait, I had explained this. Oxygen has 2 lone pairs, but we count only one into this. One thing you can keep in mind. One thing you can keep in mind. If the atom in the range, if the atom in the range has 2 lone pairs, then we have to count only one. Sir, why are we counting? Why are we counting? Okay? To solve this question, what you have to keep in mind will count only one lone pair. Okay? Now, with this, you can solve the question. Now, why only one? Because when this lone pair comes over here to form a pi bond, right? This comes over here, right? Now, after this, this oxygen becomes electron deficient. It has a positive charge on it. And electronegativity of this oxygen increases. That's why further tendency to lose this electron will not be there. Okay? That's why only one electron. Sir, there is three other electron. Only one. Okay? Anyone in the range, if the atom present in the ring has more than one lone pair to define aromaticity will count only one pair of electron. Always. Right? So one here, 2, 2 plus 2, 4 plus 2, 6 plus 2, 8, 8 pi electron anti-aromatic. Correct? This one, again, this oxygen has how many electrons? Two. But it will count only one. 2, 4, 6. So it is 6 pi electron. And it is aromatic. Okay? Sir, for nitrogen, we will also do the same thing. No, nitrogen. This lone pair, we won't count here. Because this lone pair is in the p orbital which has this lone pair, it is in different plane. See, actually, when this pi bond forms, this is because of the lateral overlap in the p orbital here. Right? So this two orbital overlap, this orbital, this orbital, this orbital, this orbital will be. So this, the p orbital which contains this lone pair, it is in different plane. It is not padline to these p orbitals here. That's why this lone pair does not, we don't count in aromaticity. Okay? So this has 2, 4, 6 pi electron. And it is aromatic. And it is aromatic. That's why I said that theory is only two, three lines. But you have to keep these examples in mind. Okay? It's also, if there's ever a copper with nitrogen in it, it can never give its proof. See, this nitrogen is sp2 hybridized. So sp2 hybridized nitrogen will not flow sexually. But sp3... Sp3 may be possible. Sp3, if it is there, it means it has already lost its electron. See, NH4 plus the orbital. When it loses its electron, it now it's sp3. NH3 is also sp3. But NH3 in the ring is not possible. Ring members are NH4 and NH3. Okay? So nitrogen, just one thing you keep in mind, nitrogen when sp2 hybridized, it won't lose its lone pair. The lone pair might be in a different orbital, right? Might be in a different side. One, that also we can see. We can define in this way also, positive charge. And you can also say that one of the p-orbiters is parallel to this p-orbiters, which has one of the lone pairs. And another one is another. That is why it's possible. It's both way you can do it. See, this compound, this compound we call it as TDD. Building is aromatic. Okay? This compound, we call it as pyrole. Sir, is that the oxidant? No, it's aromatic. No, it's the name of the oxidant. It's not... If you run, it's not that. If you run, it's something else. If you run, it's this one. See, nitrogen has sp2 hybridized. This lone pair won't take part in this present. It's not a conjugation. So this lone pair you won't come. The count will be these three pi-orbiters. One, two, three pi-orbiters. Three pi-orbiters, six pi-orbiters. As p2 hybridized, nitrogen won't give its lone pair into the conjugation. This lone pair is in different plane. Not exceptional. This lone pair is in different plane with respect to these p-orbiters. The p-orbiters which contain this lone pair and this p-orbiters are not parallel. That's why it won't... Right? Now, this one you see, here, two, four, six pi electrons and it is... it is aromatic. You see, this nitrogen is sp3 hybridized. This can come over here. Understood? Understood. What about this one? This one has a vacant orbital layer. Right? So this system is conjugated. How many pi electrons? Two pi electrons. Two pi electrons. So it is aromatic. This is also conjugated. Only one lone pair we got. So four pi electron and anti-aromantic. This is also four pi electron and anti-aromantic. The cyclic compound is not in conservation. It is not in... SPP first of all and this p-orbiters, this p-orbiters are parallel.