 We will see few examples until this how to you know write down okay now one more thing here you see one more thing is what in case of halogen okay so halogen we will discuss now so these are minus M group now the next one is plus M group or plus M effect okay plus M is what like plus I it is also has electron releasing nature in short we write it as ERG electron releasing group okay plus M has electron releasing group we also call it as plus R also plus M or plus R minus M or minus R okay for example you see if you take phenol phenol has lone pair on this oxygen atom and this is a necessary condition for any group to show plus M effect the first atom must contains lone pair on it must has excess of electron so what happens here you see this lone pair will come here and this pi electron will go here further what happens this is a resonating structure all electrons moves here this pi electron comes over here this bi-electron comes over here will get this again this bi-electron comes over here this bi-electron comes over here will yeah this okay so again there are five resonating structure 51 possible here right and what happens hear if the electron releasing Krupp is present on the benzene ring then we will get a carbon ion at ortho and para position ok. So, that is what the point you have to note down. So, note down this point if an electron releasing group attached with the benzene ring, if an electron releasing group attached with the benzene ring then carbon ion forms ortho or para. So, any electrophile here if you have they have tendency to attack on ortho and para position. Nucleophile will have tendency to attack on meta position because meta position is comparatively more electron rich ok. So, that is the point we have. Now, the next thing is who all group are there which shows plus M effect ok that is the next question. So, like I said the atoms which are attached with the benzene ring must have lone pair present on it that is the necessary condition we have. For example, you see I will write down here which shows plus M effect. So, we have plus M or plus R. So, examples we may have like the first one I have written OH we can have NH2 we can have OCH3 we can have SH, SCH3 we can have OC double bond O R halogen all these elements you see here we have two lone pair, one lone pair, two lone pair, two lone pair, two lone pair and for halogen we have three lone pair present on it ok. One more example you see we can write this one Nitrogen and derivative of this basically C double bond OCH3 this also has one lone pair present on it. Whenever the first atom contains lone pair it has tendency to show plus M effect ok. Now, one note is important here whenever an atom or group atom or molecule right atom or molecule shows plus M right on shows mesomeric inductive effect when an atom or molecule shows mesomeric and inductive effect both then mesomeric effect is the dominating effect except in case of halogen ok. This is the only exceptions we have when a group shows both mesomeric effect and electron mesomeric effect and inductive effect then always mesomeric effect is dominating except in case of halogen act. So, what is the meaning of this one? So, for halogen you see for halogen like here you see it can show resonance also because the lone pair is present, but since halogen is the electronegative element. So, it has tendency to withdraw electron also right. So, this kind of tendency if it is there. So, for halogen you see the minus I effect is dominating over plus M for halogen this is the case we have right. For all other atoms or molecules plus M or minus M dominates plus I or minus I. Mesomeric effect whether it is plus M or minus M always dominates the inductive effect whether it is plus I or minus M ok. Like you see here if I take OH then obviously we have carbon here in case of phenol you see. So, this oxygen has is more electronegative than the carbon right. So, it has electron with drawing nature also because of the electronegativity of oxygen atom and since it has lone pair also. So, it has electron donating releasing tendency also, but here when it is with drawing electron it is with drawing the sigma bonded electron which is nothing but the I effect, but in resonance this lone pair is involved like we already discussed that in resonance only pi electrons or lone pairs are involved ok. So, this lone pair will it can donate to the ring and hence it shows mesomeric effect ok. In case of NH2 also it is possible because of electronegativity difference it has tendency to withdraw electrons sigma electrons at the same time it has tendency to lose lone pairs also because of resonance ok. So, here all these cases all these cases I effect and mesomeric effect both are possible, but mesomeric will be the dominating effect here ok. We will decide the properties of the molecule according to the mesomeric effect not I effect except in case of halogen ok. And why is it so because of high electronegativity if you want you can write it down high electronegative. So, this is the condition here. Now, we will see few examples on to this and we compare which effect is dominating ok. In all these examples you have to analyze what all effects are possible and which one is dominating the possible effects plus m minus m plus i minus i and which one is dominating here ok. So, you can pause the video and solve this questions I am discussing it now ok. Now, here you see nitrogen containing one lone pair on it ok. So, obviously this lone pair is involved in resonance. So, it shows plus m effect right and at the same time nitrogen being more electronegative. So, it shows minus i also, but minus plus m is dominating here ok. O CS3 shows plus m more electronegative minus i, but again the plus m is dominating ok. NH C double bond O CS3 it shows plus m minus i plus m is dominating because of lone pair also. It cannot show resonance right, but it can withdraw electron right. So, it shows only minus i effect. There is no lone pair present on it. This one shows only plus i electron releasing. This shows what electron withdrawing minus m. It can show minus m plus m and minus i, but in case of halogen we have already discussed high electronegative minus i is dominating. It shows minus m electron right. So, these are the few examples of plus m minus m plus i and minus i growth ok. Friends there are few groups which are adjusted in nature ok which has actually both characteristics depending on the you know case it can show plus m minus m plus i minus i also. Those groups we call it as adjusted group ok. So, those few groups are there that we will see now. So, these kind of group we call it as adjusted groups. These adjusted groups shows both plus m and minus m effect depending upon depending upon the condition ok depending upon the condition. For example, you see so here what happens is C H 2 plus that you have here right. This C H 2 plus has electron withdrawing tendency. So, here this group is behaving as electron releasing group which is plus m right, but here what happens this nitrogen since we have double pond also present here see plus m and minus m we have lone pair also in double pond also. So, depending on this it can show what is the condition for minus m we should have multiple pond between the first and second atom right. And the second atom should be more electronegative than the first atom. So, it satisfies the condition of minus m at the same time it has lone pair also present in the first atom which it can donate and shows plus m group also right. So, it has the it satisfies the condition of plus m group also right. So, that is why this kind of group we call it adjusted groups depending on the nature or the molecule it shows its nature ok. Like you see this C H 2 has positive charge here. So, it has electron withdrawing tendency right this has you know what we say resonance here by sigma positive charge resonance possible. So, it here it is behaving as electron releasing plus m, but now you see here this lone pair can come here this will come here and then this will go this side ok. So, here the electron releasing tendency is not there, but it has electron withdrawing tendency which is minus m effect right. So, this kind of groups we call it as adjusted groups depending on the condition it can show either plus m or minus m. There are few more groups we have I will write down the example here first one is NO, second one is VINYLE. VINYLE is this C H double bond C H 2. So, examples you see under this if you have B H 2 attached with this VINYLE group C H 2 ok. Here this molecule is behaving as electron releasing this is what plus m. Now, if this VINYLE group is attached with oxygen. So, this behaves as this behaves as electron withdrawing minus m ok. So, this is VINYLE third one is VINYLE C H 2 positive charge right and H 2 lone pair or you can also write. So, here you see it has electron releasing tendency right this is behaving as plus m electron releasing tendency plus m. This has electron withdrawing tendency. So, this is behaving as minus m ok. So, these groups which is NO then VINYLE, VINYLE these groups has both tendency plus m or minus m depending on its depending on the condition of the molecule depending on the cases we have. According to that it shows its behavior plus m or minus m this kind of groups we call it as adjusted groups ok. So, this again you have to memorize. So, this is the few you know discussion we have done for mesomeric effect the second application of resonance because you see everywhere we have resonance we have the application of resonance ok. This is the second application of resonance we have discussed ok. Now, the third application we will discuss in the next session is aromatic city ok. Thank you ok guys. So, in this session we are going to discuss the third application of a resonance which is nothing but aromaticity ok.