Chemical Bonding Overview

Let's start. Let's say hello hello hello. Can you hear me? Hello. Hello. Can you hear me? Yes. Shall we go further? Hey, you keep quiet. Hello, hello. Sit back and sit. What nonsense! You go back and sit. If... Whoever does these things, looking at the camera... I'll terminate it. Okay fine. There's water right? Okay forget it. Let's start. It's okay. Nothing happens. Keep in mind to read. Shall we start? now okay let's go chemical bonding okay we will start the topic today chemical bonding write why write question why a bond why a bond forms question why a bond forms okay it is one of the one of the knee it is the most important chapter of our chemistry entire chemistry okay Bhoot questions aate hai ok so first of all we will discuss why a bond is made ok starting a chapter is always a little time taking because context has to be built ok now people you will be quiet then only we will start more than this then my echo does if we increase more than this if you listen then easy, you are not able to hear, if you speak too fast then your head will hurt in 10 minutes so you should be comfortable, okay, so this is hydrogen, hydrogen atom, this is hydrogen atom, right, we know Hydrogen gas exist, O2 exist, N2 exist, Helium 2 does not exist, HE2 does not exist. And you have read this, why we don't do HE2 because it is already stable. Many times discussion has been done about this, that HE is stable in itself. Because you have heard a word, which we call Octet. theory, yes, octet configuration or according to octet theory, that octet configuration except except helium because what does helium make? Duplet very good what else do we do? if we have achieved the electronic configuration of 8 or 18 which is inert gases, helium, neon, krypton, argon xenon and radon, okay, so does not go into molecular form. Where does it stay? It stays in its mono-atomic form. That means, if we want to combine an atom with another atom and make a molecule, diatomic, if we make a molecule out of the same atoms, then what do we call them? What do we make by combining two atoms? Molecule. Okay, dear? Today we know that this becomes a molecule. from which one electron brings hydrogen and another electron brings hydrogen so we share them hydrogen atom hydrogen atom and it forms a H2 molecule it forms a H2 molecule right now my question is that why this H2 molecule is being formed you will give the answer H has completed 2 in the shell and the other hydrogen has also 2 electrons have become stable but my question is that these two electrons will not repel? when they will come will they share? we have done a lot of big things behind that by repulsion of electrons it also reduces the nuclear charge Z was effective, so Z-Sigma was done So when the electrons come close to each other, why are these two electrons not repelling each other? Then why is this bond getting stability? So we made a curve in this What is our energy profile in this curve? What is the profile? Energy profile What is our distance? Do you remember this curve? What did we do in this curve? What did we do to this? Zero we have done this level as 0 ok then what happened when the inter nuclear distance between them how we denoted it from r, now it is r r is a variable here when these atoms they will get closure now what is the situation here, both atoms are at a distance ok Now I will remove this from here. Let's do one thing, let's make it next to it so that you can understand it properly. Here we are at this stage, where are these two atoms? At distance. They are getting closure. closure, closure. And what will happen? What stage is this? If this is R distance, and we are going in this direction, then what is R? It is decreasing, correct? And what is this? Potential energy. Yesterday we had studied that when an electron comes near a nucleus, then what is its potential energy? It decreases. Similarly, when two atoms come close, then what is their potential energy? Dip. Potential energy down. So this potential energy is getting down, down, down, down, down, and then suddenly it gets up. Why? Because, as soon as we reach here, at this continuum, at this minima, what starts coming? What has happened here? Our R0. What is this? R0. What is this R0? This is the inter-nuclear distance. What has happened at this stage? This atom has come at this stage. Okay, then. If I try to decrease further the radius, If I decrease it from here in this direction, What I am doing is, I am trying to compress both the atoms. It means, what I tried to do here is, I compressed them more. As soon as I did it, it is becoming unstable now. So, the potential energy of this has been overshoot. overshoot. What happened to the potential energy here? It increased. If you leave it as it is, what will come back? It will come back and stop again. What does it mean? It is the most stable stability gained in this position. And what is that position? Bond formation position. So, two atoms which were existing on higher energy How much energy? They were existing on higher energy. They came forward and they signed a contract that we will share electrons and achieve a stability. Both will gain mutual stability. What does this mutual stability mean? This is my system. Two hydrogen atoms were my system. Then they made a bond and now both are my systems. Both are atom systems, but how much of their energy has come down? This much. Did you understand what I said? Now let's understand this in the sense of the figure, because you guys understand it better than numerical values. Suppose a hydrogen atom was existing at 10 joules, and this also exists at 10 joules. When they made a bond, now the total energy is 15 joules. Combined value. Did you understand what I said? So whole system gets stabilized by 5 Joules Got it? That's why bond is formed Primary reason Energy gets reduced Secondary reason Why it was formed? Still the question is That this concept That what these two electrons did to each other What are they doing now? Why they didn't repel? So why they didn't repel? Now see, this shell is rotating electrons clockwise, this also clockwise suppose, both clockwise When a charged particle spins on its axis, earth is rotating sun and on its axis also, what is it doing on 23 degree axis? It is rotating, it is spinning also, so it is rotating while spinning. Similar system of our earth and its electron and nucleus so what does electron do? it spins and also spins so when a charged particle spins, what does it become? magnet what does it become? have you read it? if not, then read it understand it when any charged particle spins on its axis then it has created a dipole inside itself magnetic dipole has been formed one part of it has become north pole and the other part means the electron is small, its front face is north pole and lower face is south pole means it releases a magnetic field like earth north and south now there are two electrons, two magnets these electrons are coming near while spinning right if they face north pole, what will happen? Ripple that's why whenever electrons make bond Whenever we make an electron bond, what do we have to do with its spin? have to be opposite to each other why? because if face of north pole is opposite to face of south pole then what will happen? they will get stabilized they will allow each other to stay there they will not attract each other they will allow each other to stay there so what will happen in that orbital? both electrons will persist and then it will be called as a bond This is a limit, we have deliberated it. Here the molecule has come. Now it is not that the molecule will run here on its own. Till some molecule is formed here. Now due to some reason, some external force came or some collision happened that the molecule was completely compressed. As soon as it was compressed, what happened to its potential energy? It rose. As soon as it decompression happened, as soon as the collision was removed, the molecule relaxed, where did it come back? At its inter-nuclear distance. Did you understand what I said? External forces can come, right? How? Some molecule collided with it. So when the molecule collides, can't there be compression? And when there is so much compression that when it comes back to its mean position, it can happen that this bond breaks. That is the bond dissociation. Am I correct? So now slowly you are visualizing in the world of molecules that why molecules break When enough energy is available, then the bond can break It is necessary that something is broken just like this We press it so much that their inter forces get so much distorted that when we leave them, they break I can break it like this too It is not necessary to break it by doing this. Now, do you understand the sense? Why is this curve coming? This is stress condition. This is again a stress condition. This is mean position. So, molecules stay at mean position, in lowest energy state. Did you understand? Why did the bond form? Because of this anti-spin principle. Anti-spin means, this principle will become the governing principle in valence bond theory. that whenever bonds are formed, anti-spin will have to happen what did Hund's rule say? Pauli's exclusion principle no two electrons can have the same set of quantum numbers opposite spin has to be done in one orbital did you understand the reason? ok, let's move ahead now you understood the main reason of forming bonds it behaves like a spring How do you do it? What do you find in spring? Hooke's law. What is Hooke's law? Force equal to minus kx. This is it, right? Do you remember something? You study in 9th and 10th. What are you talking about? Okay. You didn't study force equal to minus kx there. Ok, no problem. We will do it. It will come in your physics. If it is not there, I will erase it. Here, nothing is called Huxlow. Ok. Write. Octet theory. I told you. Ok, you want to write this. Write. A bond forms between two atoms. A bond forms. between two atoms a bond forms between two atoms two atoms in order to in order to in order to minimize in order to minimize their energy or to gain stability by completing their duplet or octet ok now when bond is made So bonds are made in two ways. you know that we study two types of bonds one is ionic bond and other is covalent bond and third class is coordinate bond We will study it later. Weak bonding, like this hydrogen bond also happens. Vendor wall forces of attraction also happens, interactions also happens. All of them are weak sections. We call them London forces. Okay. In that dipole-dipole, induced dipole, vendor wall forces, all are included. Okay. It is separate. We will study it in states of matter. What? Metallic bond is like a covalent bond because what is happening in it? There is only one interaction between metal and metal. So it will be covered in that. Covalent bond. The main discussion of this chapter, the entire 90% discussion will be on this. Bond, the covalent bond. Okay. For which Linus Pauling got the Nobel Prize. they developed the theory of covalent bond ok all bonding prints, most of the discussion will be on covalent bond what is ionic bond? transfer of electrons what happens here? transfer of electrons and you saw this in last periodic classification that what happens? between highly electronegative and highly electropositive atom this bond What does sodium do? One electron release. Is your milestone test on Wednesday? Yes, date is coming. 29th is the milestone. Are you guys preparing? Ok, let's go. Now, what happened? Electron released, what did chlorine do? Electron accepted and what happened? Chloride became ion. Similarly, what happened in this? What did hydrogen do? Hydrogen shared one electron with it, its octade dupleted and its dupleted too. What happens in coordinate bond? Covalent bond is formed in coordinate bond too. Listen, what happens in a coordinate bond? Covalent. But what happens in this is that both the electrons come from the same atom. Means, like nitrogen. So the lone pair of nitrogen, it donated hydrogen and made a bond. Like this. Means, this is a covalent bond only. But who is sharing both? Nitrogen is there, it had electrons but it put it in bond. So what happened? Hydrogen's two electrons got completed. Who came here? H+. H didn't come. If H was there, then it would have one electron. H+, no electron came. So hydrogen had to make bond. So hydrogen plus says, H plus says I don't have electrons. So nitrogen says I will provide the electron. You just share the orbital. Yes, we will discuss that today. We will make them too. What? Does H plus have electrons? Yes. No. So how will it make a bond? It cannot. One central principle for the whole chemistry. There will be two electrons in one bond. Keep this in your mind always. How many electrons in one bond? How many will be in 3 bonds? In 3 bonds? In 2 bonds? So this principle will always be there. If there is any exception, then we will consider it in that exception. But there is no 99% exception. In 1 bond, 2 electrons. Now H plus has to be made with nitrogen, how to make it? So H plus request can only do this with nitrogen that You give me your 2 electrons, I will share, I will provide my orbital. This will be orbital. So, we will just do overlapping and what will happen? Two electrons will come in the bond. Now it has been converted into a Covalent bond Covalent bond but will be called Coordinate Covalent Bond Because Covalent's principle is Sharing Did you share? Yes But who came first to share? Nitrogen So we will say this much Donated by one atom but shared by both Agree? So write it What? We will do it now right? Now write topic levis.structure levis.structure Did you make? Everyone? Let's come Make of ozone Come on, first make simple Come on, you know Make of H2 Okay, come on, make of F2 Chlorine molecule Make of F2 F2 When was it made? In 9th? In 10th Make of F2 Make of Cl2 Make of HF Make of NH3 Make of O3 Make of CO2 Make of SO2 ok then make H2O2 make it make it make NO make NO2 make CO3-2 I know 3-1 You know it right? You knew it What is the meaning of levice dot structure? Stand up and tell me What is the meaning of levice dot structure? Let's understand the fundamentals first and then make it easily. You know it, I know it. The meaning of the Lovitz dot structure is either it will complete its duplex or its octet. But whenever it will complete it, its outer electrons will show with a dot or cross. So, every atom will try to complete its octet by sharing. Okay? or if you have made ionic bond by transfer then show by transfer ok now show me their octet structures one by one sanvi come make it what are you waiting for ok good make it make it It's a chlorine, son. F2. It's not F. Yeah. Hmm. Okay. Very good. Make it. Mansoor. Yeah. Make it. Make it. Make it. It will be made, right? So make it. Always show only the outermost electron. I wrote H2O. Yes, I will tell you now. It is wrong. I know how far you can make it. What a mess! You started? Yes. Did you make this or not? No, it's not. This is done. This is done. This is done. HF is not done. So, do it. Gargi, this should be done. Shruti, do it. Son, remember one thing. Who knows, he also makes it. Sometimes you think this by taking it for granted, I know this. Don't follow the command of the mind, follow the command of the teacher. I said make it, you make it. It is beneficial for you. Outermost of fluorine. Outermost of the second fluorine. Ok, simple. How many electrons did fluorine share? Means, by sharing one by one, two electrons came in one bond. So how much will be F? Single bond. When each electron will be sharing, how many bonds will be formed? One. If two electrons will be sharing, then double. N2? N2. How many bonds will be formed in N2? Three. Ok, make that too by sitting. We will make N2 also. Okay? We will make O2 also. Make it. It is done, son. If it is done, then make it. No. Come on, when we will make it, we will show it. whose here it is clear Cl2 Hf Hf is done so don't make Hf NH3 all O3 couldn't make so start with O3 what is the rule of Leavis Dot structure then only your octet should be complete ok Oxygen, oxygen, oxygen Okay, outermost of all Now, Ghanat, stop Now, learn I know, there must be some problem Some concept is stuck somewhere in the middle So, let's solve it 2, 4, 6 2, 4, 6 2, 4, 6 Okay Showed outermost of all, 666 How much oxygen does it need? 2 So let's do 2 shares It is done Its shortage is completed It is done How much does it need? 2 Its shortage is completed Now if it shares one electron with it, it will be accessed Agree or not? Agree? It needs two electrons. Its deficiency is complete. If it shares one electron with it, then its outer will be nine. Do you agree or not? So this problem of central atom will always remain. So what to do? If we want to make ozone, then we have to keep three oxygens together. And we have to make at least one bond. then only they will be connected otherwise one will be separated will it happen? so what should I do? listen with this oxygen both electrons will share with it so this will happen 6 of this oxygen electrons will be intact like this and these two electrons what did I do? I showed them in this bond and which bond is formed? coordinate from where it is coming? from above, this side so where did you show the arrow? here, understood? but listen to me, listen to the whole thing you are always in your own confusion when I will complete it, then all your confusion will be solved listen, who gave the electron? What will be the charge on that oxygen? Plus 1 What will be the charge on this? When the pair comes, it is plus 1 When it goes, it is plus 1 How many electrons did it have? And its octet was complete So the octet of all three oxygens did you complete the octet or not? did you complete it? did any charge come from outside on this oxygen? did any charge go outside? what is the overall molecule? what happened? ok fine, look here what is O3? it was neutral earlier also, still? why? plus one? minus 1, 0 did you get it? did any charge come from outside? no, did any charge go outside? no, it was neutral, it is neutral what did it show, plus 1, minus 1 it donated, got minus 1 there plus 1, did you understand O3? make it, right son? it was wrong, it made 2 arrows Otherwise, this notation is wrong. Wrong is wrong. If you are not in front of me, you say, sir, check this and go. What will I do with it? Will you follow the notation? Will do, coming. Have you made CO2? Made? 4, yes, do it. Make CO2, Sanvi. This is cobalt. Write capital symbol of both elements. Oh, you will confuse yourself. Write, make CO2. We will check now. We will see, we will see. Come on. Didn't read? Then we have to make it. In which? Let it be. Can SO2 be extra? Why not in SO2? Can it be 10? What's the matter? Show me. S2 6 is there. 6 is there. Ok. Oxygen. Now what to do? This is also complete. Make a negative bond. So what happened? This is also complete and this is also complete. So did it get 8 or not? How much will this be? Plus or minus? But we show it many times in this way. Let's show it like this. So, this is... In the future, the limitation of the octet theory will be that it becomes an expanded octet. We will see further. Yes, it is fine. It is made of CO2. The shape does not look like this. See, CO2 means oxygen. Yes, the size is the size. Sai Sarthak, Sai Prasad Ok How much oxygen do we need? 2 Let's write 2 in front of it How much does it need? 2 And there are 4 in the carbon outermost So it has shared 2, it has shared 2 It is complete No problem, ok It is complete It is complete And this carbon is also complete Did you do this? Ok, ok, ok I know you will not have any problem in this Done. What structure did you make? Why is this structure like this? Why is it not like this? We will discuss this later. Okay. Now we just focused on the Lewis dot structure. Raise your hand if you want to explain this or else I will move ahead. Done. CO2 clear. Let's move ahead. Make H2O2. Leave SO2 now. We will tell you later. We will discuss this later. Okay. SO2 Make H202 What else we are discussing? H202 Yes, okay Good Page like structure but ok, I am not seeing the shape in the structure Now we just Yes, son, we will make HNO3 H202 hmm after H2O2 make it of TO I am coming now, you make TO and I will make CO Yes, let's go. It's correct. H2O2. Hasn't H2O2 expanded the octet? No. Why did you make a double bond in the middle of oxygen? Can someone make three bonds in oxygen? No, right? Then whose H2O2 did not become? H2O2. No, it won't. Listen, this is oxygen, this is oxygen, this H, this H. If it needs one electron, then oxygen shared it with it. If it needs one electron, then it shared it with it. This confusion can happen to you that should I put oxygen on one side, both H? This is genuine confusion. but with time you will be clear about peroxide bond for now i am saying one oxygen has one hydrogen and other oxygen has another hydrogen so this bond is made this also clear how many electrons are left now 5 this also has 5 so we have shown two lone pairs here one electron is shown in between this one oxygen makes only two bonds ok so now shown this lone pair of this Are the whole of it 1,2,3,4,5,6,7,8? So this structure became HOOH. In H2O2, we can easily explain this molecule with the lavish dot structure. What exercise we are doing now? We are trying to find out what is the octet theory? is it able to explain our bonding or not so it has done some molecules till now F2, Cl2, HF, NH3, O3, CO2 H2O2, now we will make CO ok, H2O2 is made now make CO we will see, let's see CO Don't worry, we will do it. If there is a problem, this will be the limitation of the Leavish structure. Whenever there is a problem, understand what is happening in the Leavish Octet theory. It is at the stage of fail. Then only VBT will come. Right? Carbon. Here it is. Lovage dot structure. Dot. Dot. Dot. It has only one neighbor. Oxygen. How many electrons? Six. Two. Four. Six. Right? How many bonds does oxygen make? Two. Carbon has two electrons. and shared oxygen oxygen shortage is complete more oxygen bond can't be made what to do? tell me what to do? what? yes, there is a limitation So what is it? It has an electron pair. Now what will it do? If we talk about it till now, then how many are there in its octet and how many are there in its? Here is 6 and how many have become here? 8 Oxygen is electronegative. If any carbon lone pair is sitting next to oxygen, then oxygen cannot tolerate it. So what will it do? will make a dative bond will it happen? will this be made or this will be made? what will be the benefit of donating this? will it happen? will it not happen? did the carbon shortage be fulfilled by this? no it did not happen that means dative will not be made on this side then what will be made? Oxygen will become this. Now how many are completed? 8 and his 8 were completed. Now you will keep quiet and will tell something. Till I tell this, till you don't understand. But if you listen calmly, then only you will understand. See, what happened Sai Prasad? Who is calling? Why are you calling? Let's go. Let's teach how to make it again. Did you understand till here? What is it now? Oxygen has two lone pairs and carbon has one lone pair. Now what to do? We have to complete the octet of carbon. Who should be donated? Oxygen will do it. Because if carbon donated, then what will happen in the outer of oxygen? Ten electrons. And there will be only six of carbon. So that is not a problem. So in the octet theory, we have to see that whose... 8 electrons can be formed without any disturbance means to gain maximum stability then octet has to be completed ok, so what will I do C, bond oxygen, now the lone pair which is near this will remain after this what will happen this lone pair will come here and what will be this This will be in compulsion. What will happen? In compulsion. Otherwise, if carbon has a lone pair and oxygen does not pull it, it will not happen. What do most of the electronegative atoms do? They pull electrons. So what will happen here? What will come here? Plus. And what will come here? Minus one. Now if you count electrons. 1, 2, 3, 4, 5, 6, 7, 8. 1, 2, 3, 4, 5, 6, 7, 8. 8 of this is completed and 8 of this is completed Tell me what to explain in this Third bond is an exceptional bond formed for completion of the octet of carbon He has shared it, right? How many lone pairs were there in oxygen? There were not 6 lone pairs There are two loan pairs with Oxygen. One has shared with two bonds. So how many lone pairs were left? This and this. Now see how many are left. Where did one lone pair go? Inside the bond. Here it is. This one. One electron of this one and one electron of that one. Donated and shared. Donated not completely donated. It is partial donation. What happens in coordinate bond? Both come from one side. Will come Raise your hand if you didn't understand Didn't understand What didn't you understand? Now tell me Did you understand that ozone came? How? What we did in ozone What did we do in ozone? There were three lone pairs What did he do? He made a bond with it How many lone pairs were left? Tell me He had 6 He had 8 How many do he have now? He has 8 Because 2, 4, 6, 8 If he shares it, what will he get? Access If he shares carbon with it, what will he get from oxygen? Access Can I access it? No, I can't If I access it even if I share it, then the lack of carbon is not complete. Sharing is done to gain mutual stability. Carbon has been shared, so it has been accessed, so nothing has happened to it. So what did I have to do then? I had to make that lawn pair available to the carbon from oxygen. There was no difference in oxygen. There were 8 oxygen pairs. What happened here? it has 6 but it has given its electrons in dative bond it has disappeared and arrow has come here so what has become? its 8 has been completed and it already had 8 that is the concept of coordinate covalent similarly here don't make circle, this is understandable I am not asking you to make circle You should understand from where the electron is being donated Make next, make NO NO Is it easy? Then make it Don't make NO No, Let's see now. How? You have separated 5 electrons of nitrogen and made 3 bonds separately. Yes, let's start. Say, say, say. What? Means say again. Why not call? Wear it. You say that he shared with him, he will share with him too. Okay, he will do it, why not? 2, 4, 6. Now what are you saying? That he is like this. Then why did you do this? Why did you circle him here? For him? So when he shared him, won't he share him? Then he should be like this. Coordinate bond concept is mutual sharing. If you will do it, we will also do it. You did this, who will do this? So, 2, 4, 6, 8, 10 is there in it. Is it done? Wrong. Now, let's make it. Listen, make one electron. No. What will come? Oxygen? It's done? Oxygen's deficiency is over? Listen, bro. At least listen to the whole thing. Oxygen is over. Who is left now? Nitrogen's deficiency. Think how to complete it. What to do? Not a single electron will come. What to do? Even if we donate, it will not happen. So what to do? Can't do anything. After doing this, listen, listen to the whole thing. These two electrons, which of nitrogen and oxygen is electronegative? So these two electrons which are left, which will go into which? And what will remain with it? Now you calm down. Yes, listen to it. It is an exception. According to the structure of the levy dot, this structure is not possible. Now what will come? Minus 1 and what will come on this? First one. Did you understand? Because if I make a dative bond from here or from here, then also nothing is achieved. If I make it from here, then what will happen? 1, 2, 3, 4, how many are there? 1, 2, 3, 4, 5, 6, 7, 8 are there. If NO shares these two electrons, then also how many are there? 7. 7 are there. If oxygen shares, then how many are there? Tell me. Tell me. How will it become 8? It is 5, right? If it gives 2 1, 2, 3, 4, 5, 6, 7 No, no, this is wrong See, let's make it again Nitrogen, right? Oxygen, how many electrons? 2 are there Now how many are left? 4, how many are left? 3 Either he can share or he can share Slowly So what will happen if I disappear it from here? This Now how many are there? 6 And 3 9 Did he get stability? Still it was odd, it is odd before also So that's why No Can't do anything So what will happen? What structure will come out instead of this? This, this, this, this and this will come like this. Okay, did you understand the thing? So what will come on this? Minus 1 and what will come on this? Plus 1 Moving forward, we will also check whether there is plus 1 on this or not. He donated, right? Where is this coming from? From nitrogen. So when it is coming from nitrogen, both the electrons are coming from nitrogen So whoever we go to, it will make a charge of minus 1 and whoever we go to, we will make a charge of plus 1 This was also made in CO This is called Odd Electron Species What will you say? Odd It is an exception to Levy's, this will be the limitation of Levy's Octet Theory Why are odd electron species existing? if octet theory is the governing principle then why the species of odd electron species is existing ok now let me teach you one more exception make PCL5 what will you do sitting here? make the structure you start talking and get bored very quickly what? So do 10th class 4-5 times for 5 years only. When you don't want to learn anything new. Did you make it? What is not happening? Show me. This is of carbonate. This is of earlier. Sir, I don't understand now. So learn as I am teaching. What did you not understand? Ask. Did you raise your hand? If you didn't come, then ask at the end of the class. Yes. What did you do? Okay. PCl 5, 7, Phosphorus 5 So make it then How many bonds does chlorine make? One? He will make only one, son. It's an exception. Let's see how much will come in its octet. PCL5 exists and single single bond is obtained. PCL 5 is an example of expanded octet. Limitation of octet theory. Okay. Now write limitations of octet theory. Limitations of octet theory. What happened? Did you not write? Did you write? Listen to me. Now understand the crux of the discussion. Sometimes you got odd electron species in the form of NO Sometimes you got expanded octet in the form of PCl5 If you make the structure of BCl3 Then how many will be in the outermost of boron? How much is boron? 5 How many will be in the outermost? 3 How many will be after sharing? 6 So how many will be in its outermost? 6 How many will be in its outermost? 10 How many are there in its outermost? 7. Odd electron, deficient octet, expanded octet. With this theory, your compounds are not being explained. That's why we need an improved theory. And that's why in which picture did we come? Valence bond theory. Did you understand? Okay. Limitation samajh aayi? Likho. Octet theory could not explain. Octet theory could not explain. Octet theory could not explain. Haan bolo. Octet theory could not explain. Odd electron species could not explain the odd electron species stability. Odd electron species. Oh, my message. Sorry, I forgot. It's so cold here. I used to do it. Wait a minute, son. It's cold. It will freeze. Please. What is this room number? You two, you go out. Come on. Leavis octet could not explain the odd electron species, electron deficient species like BCL3, BCL3, ALCL3. species bcl3 recovery lcl3 randovi bcl3 comma expanded octet expanded octet molecules like pcl5 expanded octet molecules like pcl5 yes lewis octet octet theory could not explain the odd electron species comma electron deficient species like bcl3 comma expanded octet species like pcl5 comma hclo4 hclo4 right so3 so3 chloric acid yeah they are called as oxochloric acid HClO4, HClO3, HClO2, HClO ok, perchloric acid, chloric acid, chlorate all will be called ok, did you write it guys? now write it put the title valence bond theory ok, write one more limitation octet theory could not explain the shape of the molecules octet theory could not explain the shape of the molecules no information about the shape ok rest of the levis dot structure you will make it yourself which all are left? carbonate is left NO2 is left PCL5 you will make it yourself will you make it? you will never make it ok now put title valence bond theory what was the problem of octet theory the problem of octet theory was that it didn't talk about orbital it just said that so many electrons are sharing ok now write valence bond theory what is valence bond theory orbital overlap approach orbital overlap approach ok we will try to explain this through orbital overlap ok now listen What are you talking about? I don't like this. What are you guys talking about? What kind of discussion do you guys have? What is your name? Come out. Come out. You go stand there. Go. Stand there. No, no, no, no sorry. What nuisance have you guys kept? Yesterday also there was a class. More or less, the class was fine. You guys are so noisy, don't know why you disturb? You don't obey at all. Write, write, write all this. Yes. This is your treatment. You don't want to study. No, you too. Who are you? You are involved in these things. If everyone talks for 2-2 minutes, then 1.5 hours pass. Sometimes he will disturb, sometimes he will talk to him, sometimes he will talk to you, sometimes he will do it to him. Is there any such study? Many times I requested you people, you do preparation of JEE, you behave like a serious student. Nonsense. You keep creating. Total nuisance. The one who knows, he talks about himself. The one who doesn't know, he talks about himself. What kind of a way is this? You start playing games. Are you kids? You are told by 7th or 8th grade kids. You don't feel like teaching like this. You are not in school right now. You have come here with your own decision to study. These kids also read. If they are pointed at a little, they become quiet. Okay, they also talk sometimes, but they become quiet when they speak. Why do you behave like this? And how much to explain, kids? Even in explaining again and again, there is embarrassment. I can't do all this. Now you know what will happen? Now what will I tell you? Orbital overlap happens. What you want to tell, it cannot happen then. Even if you feel like delivering some extra things, even then, with your discussion, which is going on right now, it washes out all this from your mind. Everyday the same thing, how much should I guide you guys, that keep quiet, keep quiet, keep quiet. You can't sit quietly for 1.5-3 hours. What advance paper will you give for 6 hours? You have to sit there for 6 hours and give the exam. You can talk to them too. same thing has to be told in repetitive manner, you guys have to keep quiet write the title valence bond theory in valence bond theory, the concept which we will discuss that here one atom has its own orbital valence orbital and other atom has its own valence orbital their overlapping will happen ok, now when overlapping will happen, Kali Prasad You stand up. Stand up. Yes, your name. Not you, you. Yes, Neel. You stand up. You stand up there. Go. As soon as I start teaching, you start talking small things. Keep quiet means, keep quiet, kids. See, it's a simple thing. If you want to study, then study. If you don't want to study, then go. I am giving you 30 seconds time, who doesn't want to study, can go and vote. If you are bored, irritated, you don't feel like studying for 2.5 hours, go and leave quietly, don't even tell me, I won't tell you anything. Who feels that I am tired, can go and vote. But don't disturb here at least. It is the sixth hour from the day I am teaching. This is the sixth hour in which I am teaching. I am also teaching in my discipline you are studying in third hour you are not able to maintain discipline in third hour now see valence bond theory is basically made to explain the concept of covalent bond ok in this basically what we focused on that what our orbital will do overlap because when sharing of two electrons of atoms then a common space will be created and how that common space can be created? by overlapping of the orbital these two orbital will come and share a common space and how will we show the consequence of this? like this got it? so what will be this? common space in which those electrons will remain will spend maximum time and this will be called my bond so what we have done till now, till now what we have talked about oxygen oxygen 2 electrons of this and 2 electrons of this and we have developed a theory that they have made 2 bonds how they made, where overlap happened, how much overlap happened, what strength happened no discussion was not there in the octet theory but now what is the improved concept is that electron will come, orbital will also do overlapping and in that overlapping space what will happen? sit down electrons will remain ok, in that overlapping space electrons will remain and with which spin will they remain? with anti spins with opposite spins this governing principle of VBT will be made that whatever covalent bond will be made what will happen? will overlap which orbital will overlap? those who will have unpaired electrons because electrons will be unpaired and when they will come then they will pair and bond will be made from that paired electron so overlap of half filled valence shell orbitals of bonding Atoms, okay, this is unbounded state. This is bonded state one man And now so no this overlap allows electrons with opposite spins from each atom to pair up only valence orbitals having Unpaired electrons will participate in the bonding liquid line only only valence write what I have to write only valence oh bro he said it in anger ok write only you have written the whole ok write write the first important point of this theory only valence only valence orbital having unpaired electrons only valence orbitals having unpaired electrons will valence orbitals having unpaired electrons will overlap to form a covalent bond. This is the first principle. having unpaired electrons will overlap to form a bond with opposite spins with opposite spins with opposite spins this was the main point which came out of this theory ok now we will move ahead why pairing happens? so that what can that system do to its energy? we have already discussed this next then when orbital overlap will happen then it will be like that efficient If there is an effective overlap, then what will be the strength of the bond? Increase. If there is a non-efficient overlap, then what will be there? Strength will be reduced. This is the next principle of our BBT theory. The more the extent of overlapping, the stronger the bond will be. The more the overlapping will be non-efficient, we will discuss further. how it will become efficient and how it can become non-efficient ok now if there is effective overlap then what will happen now the condition of effective overlap is if direction orientation of sub-orbital is correct then effective overlap will happen if their direction is not correct then a non-effective overlap will be made like an example I will explain from here see in this, in this the overlap of this orbital is effective overlap when one bond is formed then this orbital is in standing position vertical position, vertical position when this bond is formed, now this carbon atom can't proceed further when carbon atom can't proceed further then the orientation of these orbitals is only this Okay? so now if their interaction is also there then what kind of interaction will be there? weak interaction how will it be? that's why this bond will be called sigma in the future and this bond will be called pi bond pi bond is a weaker bond sigma bond is a stronger bond why did I tell this? for now I had to tell the orientation factor I had to tell the orientation factor that when the orbital will come head to head see, then the talks starts when orbital will come head to head will come in front of us then what will we say? overlap is going on with good orientation but after overlap now a situation is created for inorbital now an orientation is not like good because now this carbon is not going forward so now how is their orientation? non effective overlap but still there is an overlap how is the overlap? how this overlap is shown in many books I will show you this in many books you will see this overlap like this this is something like that the lobe was above this lobe this lobe of p-orbital what has happened? these orbitals have been bent what has happened? a little bit because this is not fixed how is this? like if you hold a balloon in your hand, then what happens to the balloon? it keeps on moving here and there you can understand these lobes of p orbital in this way it is just a way of representation someone does it like this, someone writes like this and makes a line understood the point? but both are the same type of bonds PP overlap How is it? There are overlaps of p-p orbital and the pi bond has formed and what are the electrons in the pi bond? pi electrons and those who are in the sigma bond, we will call them sigma electrons Okay? Did you understand this much? Okay, fine In the same way, now see p-p overlap, you understood this Now there are three types of p orbitals px, py, pz one participant must have done here for now understand that done how many are left? two so one p orbital will be like this here perpendicular lie on the other axis also one will be like this and one will be like this so the other p orbitals will be one bond is made like this the other will be seen in another color how it is seen? here it is and its electron is visible here see from the other angle, it is here means what are two electrons doing in it? they are rotating continuously, they are present now they don't know where they are they can be here or there but their zone is this right, that's why we call it switching we are making it with a pen again and again this thing we want to say that the two electrons are switching here and here again and again This is same. This switching and this switching. These are the two electrons which we are showing here and here. It is just a representation of this one. That means electron is here, here. So it is like this. In pi bond electrons are like this. And how will the other ones be in pi bond? Like this. Right? Weak overlap. But... Existing now is he go kiss the rickety-goo. Sorry sense me. I said it. I think you be way you think of the career We check a club era a club aura a key era a key era So you be pi bond hair or the a douche wrap I bond hair or beach McConaughey Sigma so orientation good orientation axial overlap effective overlap strong bond weak overlap then weak bond, pi bond formation so what was the concept of VBT if the extent of overlapping is good but with orientation then good bond will be formed means strength of the bond will increase if overlap is good but orientation is not good then overlap bonding strength of the bond will be weak That's all for today. Okay. That's all for today. Let's take it. Sit down. Why are you waiting? Who teaches Maths, sir? Sir, Linka. Do you want to make a show in his class? No? Keep quiet, sir. You are useless. The one who gets the attendance can go. Okay. Aparajit. Arvind. Shyamla. Ashlesha. Bishwaranjan. Gargi. Ghanat. Jayakrishna. Kaliprasad. Madhusmita. Megha. Monali. Om Prakash. Om. Preeti Priyanshu Rajat Rupesh Rupesh saishritam stanvi say on Shruti Shivangi so hun so hun shri hun Swayam Swayam Yashashri Divyanshu Anushka Abhishek Ayush Ritesh Ayush Swayam Pratyusha Sudipth Zinit Bignesh, Neel, Himanshu, Jignyasha, go go whoever has done it, Shubhankar, Subham, Deeptanshu, I will put it son, go you guys, Adyasha, Ayush, Rosalina. udvashi swapnali namrata sahiprasad aditya riyazuddin dvjyoti priyani ekta krishna anushka sri anshu

Let's start. Let's say hello hello hello. Can you hear me?

Hello. Hello. Can you hear me? Yes. Shall we go further?

Hey, you keep quiet. Hello, hello. Sit back and sit. What nonsense! You go back and sit.

If... Whoever does these things, looking at the camera... I'll terminate it.

Okay fine. There's water right? Okay forget it. Let's start.

It's okay. Nothing happens. Keep in mind to read. Shall we start?

now okay let's go chemical bonding okay we will start the topic today chemical bonding write why write question why a bond why a bond forms question why a bond forms okay it is one of the one of the knee it is the most important chapter of our chemistry entire chemistry okay Bhoot questions aate hai ok so first of all we will discuss why a bond is made ok starting a chapter is always a little time taking because context has to be built ok now people you will be quiet then only we will start more than this then my echo does if we increase more than this if you listen then easy, you are not able to hear, if you speak too fast then your head will hurt in 10 minutes so you should be comfortable, okay, so this is hydrogen, hydrogen atom, this is hydrogen atom, right, we know Hydrogen gas exist, O2 exist, N2 exist, Helium 2 does not exist, HE2 does not exist. And you have read this, why we don't do HE2 because it is already stable. Many times discussion has been done about this, that HE is stable in itself. Because you have heard a word, which we call Octet. theory, yes, octet configuration or according to octet theory, that octet configuration except except helium because what does helium make?

Duplet very good what else do we do? if we have achieved the electronic configuration of 8 or 18 which is inert gases, helium, neon, krypton, argon xenon and radon, okay, so does not go into molecular form. Where does it stay?

It stays in its mono-atomic form. That means, if we want to combine an atom with another atom and make a molecule, diatomic, if we make a molecule out of the same atoms, then what do we call them? What do we make by combining two atoms? Molecule. Okay, dear?

Today we know that this becomes a molecule. from which one electron brings hydrogen and another electron brings hydrogen so we share them hydrogen atom hydrogen atom and it forms a H2 molecule it forms a H2 molecule right now my question is that why this H2 molecule is being formed you will give the answer H has completed 2 in the shell and the other hydrogen has also 2 electrons have become stable but my question is that these two electrons will not repel? when they will come will they share?

we have done a lot of big things behind that by repulsion of electrons it also reduces the nuclear charge Z was effective, so Z-Sigma was done So when the electrons come close to each other, why are these two electrons not repelling each other? Then why is this bond getting stability? So we made a curve in this What is our energy profile in this curve?

What is the profile? Energy profile What is our distance? Do you remember this curve? What did we do in this curve?

What did we do to this? Zero we have done this level as 0 ok then what happened when the inter nuclear distance between them how we denoted it from r, now it is r r is a variable here when these atoms they will get closure now what is the situation here, both atoms are at a distance ok Now I will remove this from here. Let's do one thing, let's make it next to it so that you can understand it properly. Here we are at this stage, where are these two atoms?

At distance. They are getting closure. closure, closure.

And what will happen? What stage is this? If this is R distance, and we are going in this direction, then what is R? It is decreasing, correct?

And what is this? Potential energy. Yesterday we had studied that when an electron comes near a nucleus, then what is its potential energy? It decreases. Similarly, when two atoms come close, then what is their potential energy?

Dip. Potential energy down. So this potential energy is getting down, down, down, down, down, and then suddenly it gets up.

Why? Because, as soon as we reach here, at this continuum, at this minima, what starts coming? What has happened here?

Our R0. What is this? R0. What is this R0?

This is the inter-nuclear distance. What has happened at this stage? This atom has come at this stage. Okay, then.

If I try to decrease further the radius, If I decrease it from here in this direction, What I am doing is, I am trying to compress both the atoms. It means, what I tried to do here is, I compressed them more. As soon as I did it, it is becoming unstable now. So, the potential energy of this has been overshoot.

overshoot. What happened to the potential energy here? It increased.

If you leave it as it is, what will come back? It will come back and stop again. What does it mean? It is the most stable stability gained in this position.

And what is that position? Bond formation position. So, two atoms which were existing on higher energy How much energy? They were existing on higher energy. They came forward and they signed a contract that we will share electrons and achieve a stability.

Both will gain mutual stability. What does this mutual stability mean? This is my system. Two hydrogen atoms were my system. Then they made a bond and now both are my systems.

Both are atom systems, but how much of their energy has come down? This much. Did you understand what I said? Now let's understand this in the sense of the figure, because you guys understand it better than numerical values.

Suppose a hydrogen atom was existing at 10 joules, and this also exists at 10 joules. When they made a bond, now the total energy is 15 joules. Combined value. Did you understand what I said? So whole system gets stabilized by 5 Joules Got it?

That's why bond is formed Primary reason Energy gets reduced Secondary reason Why it was formed? Still the question is That this concept That what these two electrons did to each other What are they doing now? Why they didn't repel? So why they didn't repel?

Now see, this shell is rotating electrons clockwise, this also clockwise suppose, both clockwise When a charged particle spins on its axis, earth is rotating sun and on its axis also, what is it doing on 23 degree axis? It is rotating, it is spinning also, so it is rotating while spinning. Similar system of our earth and its electron and nucleus so what does electron do?

it spins and also spins so when a charged particle spins, what does it become? magnet what does it become? have you read it?

if not, then read it understand it when any charged particle spins on its axis then it has created a dipole inside itself magnetic dipole has been formed one part of it has become north pole and the other part means the electron is small, its front face is north pole and lower face is south pole means it releases a magnetic field like earth north and south now there are two electrons, two magnets these electrons are coming near while spinning right if they face north pole, what will happen? Ripple that's why whenever electrons make bond Whenever we make an electron bond, what do we have to do with its spin? have to be opposite to each other why?

because if face of north pole is opposite to face of south pole then what will happen? they will get stabilized they will allow each other to stay there they will not attract each other they will allow each other to stay there so what will happen in that orbital? both electrons will persist and then it will be called as a bond This is a limit, we have deliberated it. Here the molecule has come. Now it is not that the molecule will run here on its own.

Till some molecule is formed here. Now due to some reason, some external force came or some collision happened that the molecule was completely compressed. As soon as it was compressed, what happened to its potential energy? It rose.

As soon as it decompression happened, as soon as the collision was removed, the molecule relaxed, where did it come back? At its inter-nuclear distance. Did you understand what I said? External forces can come, right? How?

Some molecule collided with it. So when the molecule collides, can't there be compression? And when there is so much compression that when it comes back to its mean position, it can happen that this bond breaks. That is the bond dissociation. Am I correct?

So now slowly you are visualizing in the world of molecules that why molecules break When enough energy is available, then the bond can break It is necessary that something is broken just like this We press it so much that their inter forces get so much distorted that when we leave them, they break I can break it like this too It is not necessary to break it by doing this. Now, do you understand the sense? Why is this curve coming? This is stress condition. This is again a stress condition.

This is mean position. So, molecules stay at mean position, in lowest energy state. Did you understand? Why did the bond form? Because of this anti-spin principle.

Anti-spin means, this principle will become the governing principle in valence bond theory. that whenever bonds are formed, anti-spin will have to happen what did Hund's rule say? Pauli's exclusion principle no two electrons can have the same set of quantum numbers opposite spin has to be done in one orbital did you understand the reason?

ok, let's move ahead now you understood the main reason of forming bonds it behaves like a spring How do you do it? What do you find in spring? Hooke's law. What is Hooke's law?

Force equal to minus kx. This is it, right? Do you remember something?

You study in 9th and 10th. What are you talking about? Okay.

You didn't study force equal to minus kx there. Ok, no problem. We will do it. It will come in your physics. If it is not there, I will erase it.

Here, nothing is called Huxlow. Ok. Write. Octet theory.

I told you. Ok, you want to write this. Write.

A bond forms between two atoms. A bond forms. between two atoms a bond forms between two atoms two atoms in order to in order to in order to minimize in order to minimize their energy or to gain stability by completing their duplet or octet ok now when bond is made So bonds are made in two ways. you know that we study two types of bonds one is ionic bond and other is covalent bond and third class is coordinate bond We will study it later.

Weak bonding, like this hydrogen bond also happens. Vendor wall forces of attraction also happens, interactions also happens. All of them are weak sections.

We call them London forces. Okay. In that dipole-dipole, induced dipole, vendor wall forces, all are included.

Okay. It is separate. We will study it in states of matter. What?

Metallic bond is like a covalent bond because what is happening in it? There is only one interaction between metal and metal. So it will be covered in that. Covalent bond. The main discussion of this chapter, the entire 90% discussion will be on this.

Bond, the covalent bond. Okay. For which Linus Pauling got the Nobel Prize. they developed the theory of covalent bond ok all bonding prints, most of the discussion will be on covalent bond what is ionic bond? transfer of electrons what happens here?

transfer of electrons and you saw this in last periodic classification that what happens? between highly electronegative and highly electropositive atom this bond What does sodium do? One electron release.

Is your milestone test on Wednesday? Yes, date is coming. 29th is the milestone. Are you guys preparing?

Ok, let's go. Now, what happened? Electron released, what did chlorine do?

Electron accepted and what happened? Chloride became ion. Similarly, what happened in this? What did hydrogen do? Hydrogen shared one electron with it, its octade dupleted and its dupleted too.

What happens in coordinate bond? Covalent bond is formed in coordinate bond too. Listen, what happens in a coordinate bond? Covalent.

But what happens in this is that both the electrons come from the same atom. Means, like nitrogen. So the lone pair of nitrogen, it donated hydrogen and made a bond. Like this.

Means, this is a covalent bond only. But who is sharing both? Nitrogen is there, it had electrons but it put it in bond. So what happened? Hydrogen's two electrons got completed.

Who came here? H+. H didn't come. If H was there, then it would have one electron.

H+, no electron came. So hydrogen had to make bond. So hydrogen plus says, H plus says I don't have electrons. So nitrogen says I will provide the electron. You just share the orbital.

Yes, we will discuss that today. We will make them too. What?

Does H plus have electrons? Yes. No.

So how will it make a bond? It cannot. One central principle for the whole chemistry. There will be two electrons in one bond. Keep this in your mind always.

How many electrons in one bond? How many will be in 3 bonds? In 3 bonds?

In 2 bonds? So this principle will always be there. If there is any exception, then we will consider it in that exception.

But there is no 99% exception. In 1 bond, 2 electrons. Now H plus has to be made with nitrogen, how to make it? So H plus request can only do this with nitrogen that You give me your 2 electrons, I will share, I will provide my orbital.

This will be orbital. So, we will just do overlapping and what will happen? Two electrons will come in the bond. Now it has been converted into a Covalent bond Covalent bond but will be called Coordinate Covalent Bond Because Covalent's principle is Sharing Did you share? Yes But who came first to share?

Nitrogen So we will say this much Donated by one atom but shared by both Agree? So write it What? We will do it now right? Now write topic levis.structure levis.structure Did you make?

Everyone? Let's come Make of ozone Come on, first make simple Come on, you know Make of H2 Okay, come on, make of F2 Chlorine molecule Make of F2 F2 When was it made? In 9th?

In 10th Make of F2 Make of Cl2 Make of HF Make of NH3 Make of O3 Make of CO2 Make of SO2 ok then make H2O2 make it make it make NO make NO2 make CO3-2 I know 3-1 You know it right? You knew it What is the meaning of levice dot structure? Stand up and tell me What is the meaning of levice dot structure? Let's understand the fundamentals first and then make it easily.

You know it, I know it. The meaning of the Lovitz dot structure is either it will complete its duplex or its octet. But whenever it will complete it, its outer electrons will show with a dot or cross. So, every atom will try to complete its octet by sharing.

Okay? or if you have made ionic bond by transfer then show by transfer ok now show me their octet structures one by one sanvi come make it what are you waiting for ok good make it make it It's a chlorine, son. F2.

It's not F. Yeah. Hmm.

Okay. Very good. Make it.

Mansoor. Yeah. Make it.

Make it. Make it. It will be made, right? So make it. Always show only the outermost electron.

I wrote H2O. Yes, I will tell you now. It is wrong.

I know how far you can make it. What a mess! You started?

Yes. Did you make this or not? No, it's not.

This is done. This is done. This is done. HF is not done.

So, do it. Gargi, this should be done. Shruti, do it.

Son, remember one thing. Who knows, he also makes it. Sometimes you think this by taking it for granted, I know this.

Don't follow the command of the mind, follow the command of the teacher. I said make it, you make it. It is beneficial for you.

Outermost of fluorine. Outermost of the second fluorine. Ok, simple.

How many electrons did fluorine share? Means, by sharing one by one, two electrons came in one bond. So how much will be F?

Single bond. When each electron will be sharing, how many bonds will be formed? One. If two electrons will be sharing, then double. N2?

N2. How many bonds will be formed in N2? Three.

Ok, make that too by sitting. We will make N2 also. Okay?

We will make O2 also. Make it. It is done, son.

If it is done, then make it. No. Come on, when we will make it, we will show it. whose here it is clear Cl2 Hf Hf is done so don't make Hf NH3 all O3 couldn't make so start with O3 what is the rule of Leavis Dot structure then only your octet should be complete ok Oxygen, oxygen, oxygen Okay, outermost of all Now, Ghanat, stop Now, learn I know, there must be some problem Some concept is stuck somewhere in the middle So, let's solve it 2, 4, 6 2, 4, 6 2, 4, 6 Okay Showed outermost of all, 666 How much oxygen does it need?

2 So let's do 2 shares It is done Its shortage is completed It is done How much does it need? 2 Its shortage is completed Now if it shares one electron with it, it will be accessed Agree or not? Agree?

It needs two electrons. Its deficiency is complete. If it shares one electron with it, then its outer will be nine. Do you agree or not?

So this problem of central atom will always remain. So what to do? If we want to make ozone, then we have to keep three oxygens together.

And we have to make at least one bond. then only they will be connected otherwise one will be separated will it happen? so what should I do? listen with this oxygen both electrons will share with it so this will happen 6 of this oxygen electrons will be intact like this and these two electrons what did I do? I showed them in this bond and which bond is formed?

coordinate from where it is coming? from above, this side so where did you show the arrow? here, understood? but listen to me, listen to the whole thing you are always in your own confusion when I will complete it, then all your confusion will be solved listen, who gave the electron? What will be the charge on that oxygen?

Plus 1 What will be the charge on this? When the pair comes, it is plus 1 When it goes, it is plus 1 How many electrons did it have? And its octet was complete So the octet of all three oxygens did you complete the octet or not?

did you complete it? did any charge come from outside on this oxygen? did any charge go outside? what is the overall molecule?

what happened? ok fine, look here what is O3? it was neutral earlier also, still? why?

plus one? minus 1, 0 did you get it? did any charge come from outside?

no, did any charge go outside? no, it was neutral, it is neutral what did it show, plus 1, minus 1 it donated, got minus 1 there plus 1, did you understand O3? make it, right son?

it was wrong, it made 2 arrows Otherwise, this notation is wrong. Wrong is wrong. If you are not in front of me, you say, sir, check this and go. What will I do with it? Will you follow the notation?

Will do, coming. Have you made CO2? Made? 4, yes, do it.

Make CO2, Sanvi. This is cobalt. Write capital symbol of both elements.

Oh, you will confuse yourself. Write, make CO2. We will check now. We will see, we will see. Come on.

Didn't read? Then we have to make it. In which? Let it be. Can SO2 be extra?

Why not in SO2? Can it be 10? What's the matter?

Show me. S2 6 is there. 6 is there. Ok.

Oxygen. Now what to do? This is also complete.

Make a negative bond. So what happened? This is also complete and this is also complete.

So did it get 8 or not? How much will this be? Plus or minus?

But we show it many times in this way. Let's show it like this. So, this is...

In the future, the limitation of the octet theory will be that it becomes an expanded octet. We will see further. Yes, it is fine.

It is made of CO2. The shape does not look like this. See, CO2 means oxygen. Yes, the size is the size. Sai Sarthak, Sai Prasad Ok How much oxygen do we need?

2 Let's write 2 in front of it How much does it need? 2 And there are 4 in the carbon outermost So it has shared 2, it has shared 2 It is complete No problem, ok It is complete It is complete And this carbon is also complete Did you do this? Ok, ok, ok I know you will not have any problem in this Done. What structure did you make?

Why is this structure like this? Why is it not like this? We will discuss this later. Okay. Now we just focused on the Lewis dot structure.

Raise your hand if you want to explain this or else I will move ahead. Done. CO2 clear. Let's move ahead.

Make H2O2. Leave SO2 now. We will tell you later.

We will discuss this later. Okay. SO2 Make H202 What else we are discussing? H202 Yes, okay Good Page like structure but ok, I am not seeing the shape in the structure Now we just Yes, son, we will make HNO3 H202 hmm after H2O2 make it of TO I am coming now, you make TO and I will make CO Yes, let's go.

It's correct. H2O2. Hasn't H2O2 expanded the octet?

No. Why did you make a double bond in the middle of oxygen? Can someone make three bonds in oxygen? No, right? Then whose H2O2 did not become?

H2O2. No, it won't. Listen, this is oxygen, this is oxygen, this H, this H. If it needs one electron, then oxygen shared it with it.

If it needs one electron, then it shared it with it. This confusion can happen to you that should I put oxygen on one side, both H? This is genuine confusion.

but with time you will be clear about peroxide bond for now i am saying one oxygen has one hydrogen and other oxygen has another hydrogen so this bond is made this also clear how many electrons are left now 5 this also has 5 so we have shown two lone pairs here one electron is shown in between this one oxygen makes only two bonds ok so now shown this lone pair of this Are the whole of it 1,2,3,4,5,6,7,8? So this structure became HOOH. In H2O2, we can easily explain this molecule with the lavish dot structure. What exercise we are doing now?

We are trying to find out what is the octet theory? is it able to explain our bonding or not so it has done some molecules till now F2, Cl2, HF, NH3, O3, CO2 H2O2, now we will make CO ok, H2O2 is made now make CO we will see, let's see CO Don't worry, we will do it. If there is a problem, this will be the limitation of the Leavish structure. Whenever there is a problem, understand what is happening in the Leavish Octet theory.

It is at the stage of fail. Then only VBT will come. Right?

Carbon. Here it is. Lovage dot structure. Dot. Dot.

Dot. It has only one neighbor. Oxygen.

How many electrons? Six. Two.

Four. Six. Right?

How many bonds does oxygen make? Two. Carbon has two electrons.

and shared oxygen oxygen shortage is complete more oxygen bond can't be made what to do? tell me what to do? what?

yes, there is a limitation So what is it? It has an electron pair. Now what will it do? If we talk about it till now, then how many are there in its octet and how many are there in its? Here is 6 and how many have become here?

8 Oxygen is electronegative. If any carbon lone pair is sitting next to oxygen, then oxygen cannot tolerate it. So what will it do? will make a dative bond will it happen?

will this be made or this will be made? what will be the benefit of donating this? will it happen?

will it not happen? did the carbon shortage be fulfilled by this? no it did not happen that means dative will not be made on this side then what will be made? Oxygen will become this. Now how many are completed?

8 and his 8 were completed. Now you will keep quiet and will tell something. Till I tell this, till you don't understand.

But if you listen calmly, then only you will understand. See, what happened Sai Prasad? Who is calling? Why are you calling?

Let's go. Let's teach how to make it again. Did you understand till here? What is it now?

Oxygen has two lone pairs and carbon has one lone pair. Now what to do? We have to complete the octet of carbon. Who should be donated? Oxygen will do it.

Because if carbon donated, then what will happen in the outer of oxygen? Ten electrons. And there will be only six of carbon. So that is not a problem. So in the octet theory, we have to see that whose...

8 electrons can be formed without any disturbance means to gain maximum stability then octet has to be completed ok, so what will I do C, bond oxygen, now the lone pair which is near this will remain after this what will happen this lone pair will come here and what will be this This will be in compulsion. What will happen? In compulsion.

Otherwise, if carbon has a lone pair and oxygen does not pull it, it will not happen. What do most of the electronegative atoms do? They pull electrons. So what will happen here? What will come here?

Plus. And what will come here? Minus one. Now if you count electrons. 1, 2, 3, 4, 5, 6, 7, 8. 1, 2, 3, 4, 5, 6, 7, 8. 8 of this is completed and 8 of this is completed Tell me what to explain in this Third bond is an exceptional bond formed for completion of the octet of carbon He has shared it, right?

How many lone pairs were there in oxygen? There were not 6 lone pairs There are two loan pairs with Oxygen. One has shared with two bonds. So how many lone pairs were left?

This and this. Now see how many are left. Where did one lone pair go?

Inside the bond. Here it is. This one.

One electron of this one and one electron of that one. Donated and shared. Donated not completely donated. It is partial donation. What happens in coordinate bond?

Both come from one side. Will come Raise your hand if you didn't understand Didn't understand What didn't you understand? Now tell me Did you understand that ozone came?

How? What we did in ozone What did we do in ozone? There were three lone pairs What did he do?

He made a bond with it How many lone pairs were left? Tell me He had 6 He had 8 How many do he have now? He has 8 Because 2, 4, 6, 8 If he shares it, what will he get? Access If he shares carbon with it, what will he get from oxygen?

Access Can I access it? No, I can't If I access it even if I share it, then the lack of carbon is not complete. Sharing is done to gain mutual stability.

Carbon has been shared, so it has been accessed, so nothing has happened to it. So what did I have to do then? I had to make that lawn pair available to the carbon from oxygen.

There was no difference in oxygen. There were 8 oxygen pairs. What happened here?

it has 6 but it has given its electrons in dative bond it has disappeared and arrow has come here so what has become? its 8 has been completed and it already had 8 that is the concept of coordinate covalent similarly here don't make circle, this is understandable I am not asking you to make circle You should understand from where the electron is being donated Make next, make NO NO Is it easy? Then make it Don't make NO No, Let's see now. How?

You have separated 5 electrons of nitrogen and made 3 bonds separately. Yes, let's start. Say, say, say.

What? Means say again. Why not call?

Wear it. You say that he shared with him, he will share with him too. Okay, he will do it, why not?

2, 4, 6. Now what are you saying? That he is like this. Then why did you do this?

Why did you circle him here? For him? So when he shared him, won't he share him? Then he should be like this.

Coordinate bond concept is mutual sharing. If you will do it, we will also do it. You did this, who will do this? So, 2, 4, 6, 8, 10 is there in it.

Is it done? Wrong. Now, let's make it.

Listen, make one electron. No. What will come? Oxygen? It's done?

Oxygen's deficiency is over? Listen, bro. At least listen to the whole thing. Oxygen is over. Who is left now?

Nitrogen's deficiency. Think how to complete it. What to do? Not a single electron will come.

What to do? Even if we donate, it will not happen. So what to do?

Can't do anything. After doing this, listen, listen to the whole thing. These two electrons, which of nitrogen and oxygen is electronegative? So these two electrons which are left, which will go into which?

And what will remain with it? Now you calm down. Yes, listen to it.

It is an exception. According to the structure of the levy dot, this structure is not possible. Now what will come?

Minus 1 and what will come on this? First one. Did you understand? Because if I make a dative bond from here or from here, then also nothing is achieved.

If I make it from here, then what will happen? 1, 2, 3, 4, how many are there? 1, 2, 3, 4, 5, 6, 7, 8 are there. If NO shares these two electrons, then also how many are there?

7. 7 are there. If oxygen shares, then how many are there? Tell me. Tell me. How will it become 8?

It is 5, right? If it gives 2 1, 2, 3, 4, 5, 6, 7 No, no, this is wrong See, let's make it again Nitrogen, right? Oxygen, how many electrons? 2 are there Now how many are left? 4, how many are left?

3 Either he can share or he can share Slowly So what will happen if I disappear it from here? This Now how many are there? 6 And 3 9 Did he get stability?

Still it was odd, it is odd before also So that's why No Can't do anything So what will happen? What structure will come out instead of this? This, this, this, this and this will come like this.

Okay, did you understand the thing? So what will come on this? Minus 1 and what will come on this? Plus 1 Moving forward, we will also check whether there is plus 1 on this or not. He donated, right?

Where is this coming from? From nitrogen. So when it is coming from nitrogen, both the electrons are coming from nitrogen So whoever we go to, it will make a charge of minus 1 and whoever we go to, we will make a charge of plus 1 This was also made in CO This is called Odd Electron Species What will you say? Odd It is an exception to Levy's, this will be the limitation of Levy's Octet Theory Why are odd electron species existing?

if octet theory is the governing principle then why the species of odd electron species is existing ok now let me teach you one more exception make PCL5 what will you do sitting here? make the structure you start talking and get bored very quickly what? So do 10th class 4-5 times for 5 years only.

When you don't want to learn anything new. Did you make it? What is not happening?

Show me. This is of carbonate. This is of earlier.

Sir, I don't understand now. So learn as I am teaching. What did you not understand?

Ask. Did you raise your hand? If you didn't come, then ask at the end of the class.

Yes. What did you do? Okay. PCl 5, 7, Phosphorus 5 So make it then How many bonds does chlorine make? One?

He will make only one, son. It's an exception. Let's see how much will come in its octet.

PCL5 exists and single single bond is obtained. PCL 5 is an example of expanded octet. Limitation of octet theory. Okay. Now write limitations of octet theory.

Limitations of octet theory. What happened? Did you not write? Did you write?

Listen to me. Now understand the crux of the discussion. Sometimes you got odd electron species in the form of NO Sometimes you got expanded octet in the form of PCl5 If you make the structure of BCl3 Then how many will be in the outermost of boron?

How much is boron? 5 How many will be in the outermost? 3 How many will be after sharing?

6 So how many will be in its outermost? 6 How many will be in its outermost? 10 How many are there in its outermost? 7. Odd electron, deficient octet, expanded octet.

With this theory, your compounds are not being explained. That's why we need an improved theory. And that's why in which picture did we come?

Valence bond theory. Did you understand? Okay.

Limitation samajh aayi? Likho. Octet theory could not explain. Octet theory could not explain. Octet theory could not explain.

Haan bolo. Octet theory could not explain. Odd electron species could not explain the odd electron species stability.

Odd electron species. Oh, my message. Sorry, I forgot.

It's so cold here. I used to do it. Wait a minute, son. It's cold. It will freeze.

Please. What is this room number? You two, you go out.

Come on. Leavis octet could not explain the odd electron species, electron deficient species like BCL3, BCL3, ALCL3. species bcl3 recovery lcl3 randovi bcl3 comma expanded octet expanded octet molecules like pcl5 expanded octet molecules like pcl5 yes lewis octet octet theory could not explain the odd electron species comma electron deficient species like bcl3 comma expanded octet species like pcl5 comma hclo4 hclo4 right so3 so3 chloric acid yeah they are called as oxochloric acid HClO4, HClO3, HClO2, HClO ok, perchloric acid, chloric acid, chlorate all will be called ok, did you write it guys?

now write it put the title valence bond theory ok, write one more limitation octet theory could not explain the shape of the molecules octet theory could not explain the shape of the molecules no information about the shape ok rest of the levis dot structure you will make it yourself which all are left? carbonate is left NO2 is left PCL5 you will make it yourself will you make it? you will never make it ok now put title valence bond theory what was the problem of octet theory the problem of octet theory was that it didn't talk about orbital it just said that so many electrons are sharing ok now write valence bond theory what is valence bond theory orbital overlap approach orbital overlap approach ok we will try to explain this through orbital overlap ok now listen What are you talking about? I don't like this.

What are you guys talking about? What kind of discussion do you guys have? What is your name? Come out. Come out.

You go stand there. Go. Stand there. No, no, no, no sorry. What nuisance have you guys kept?

Yesterday also there was a class. More or less, the class was fine. You guys are so noisy, don't know why you disturb? You don't obey at all. Write, write, write all this.

Yes. This is your treatment. You don't want to study. No, you too. Who are you?

You are involved in these things. If everyone talks for 2-2 minutes, then 1.5 hours pass. Sometimes he will disturb, sometimes he will talk to him, sometimes he will talk to you, sometimes he will do it to him. Is there any such study? Many times I requested you people, you do preparation of JEE, you behave like a serious student.

Nonsense. You keep creating. Total nuisance.

The one who knows, he talks about himself. The one who doesn't know, he talks about himself. What kind of a way is this?

You start playing games. Are you kids? You are told by 7th or 8th grade kids. You don't feel like teaching like this.

You are not in school right now. You have come here with your own decision to study. These kids also read. If they are pointed at a little, they become quiet.

Okay, they also talk sometimes, but they become quiet when they speak. Why do you behave like this? And how much to explain, kids? Even in explaining again and again, there is embarrassment. I can't do all this.

Now you know what will happen? Now what will I tell you? Orbital overlap happens.

What you want to tell, it cannot happen then. Even if you feel like delivering some extra things, even then, with your discussion, which is going on right now, it washes out all this from your mind. Everyday the same thing, how much should I guide you guys, that keep quiet, keep quiet, keep quiet.

You can't sit quietly for 1.5-3 hours. What advance paper will you give for 6 hours? You have to sit there for 6 hours and give the exam. You can talk to them too.

same thing has to be told in repetitive manner, you guys have to keep quiet write the title valence bond theory in valence bond theory, the concept which we will discuss that here one atom has its own orbital valence orbital and other atom has its own valence orbital their overlapping will happen ok, now when overlapping will happen, Kali Prasad You stand up. Stand up. Yes, your name.

Not you, you. Yes, Neel. You stand up.

You stand up there. Go. As soon as I start teaching, you start talking small things. Keep quiet means, keep quiet, kids.

See, it's a simple thing. If you want to study, then study. If you don't want to study, then go. I am giving you 30 seconds time, who doesn't want to study, can go and vote. If you are bored, irritated, you don't feel like studying for 2.5 hours, go and leave quietly, don't even tell me, I won't tell you anything.

Who feels that I am tired, can go and vote. But don't disturb here at least. It is the sixth hour from the day I am teaching.

This is the sixth hour in which I am teaching. I am also teaching in my discipline you are studying in third hour you are not able to maintain discipline in third hour now see valence bond theory is basically made to explain the concept of covalent bond ok in this basically what we focused on that what our orbital will do overlap because when sharing of two electrons of atoms then a common space will be created and how that common space can be created? by overlapping of the orbital these two orbital will come and share a common space and how will we show the consequence of this?

like this got it? so what will be this? common space in which those electrons will remain will spend maximum time and this will be called my bond so what we have done till now, till now what we have talked about oxygen oxygen 2 electrons of this and 2 electrons of this and we have developed a theory that they have made 2 bonds how they made, where overlap happened, how much overlap happened, what strength happened no discussion was not there in the octet theory but now what is the improved concept is that electron will come, orbital will also do overlapping and in that overlapping space what will happen?

sit down electrons will remain ok, in that overlapping space electrons will remain and with which spin will they remain? with anti spins with opposite spins this governing principle of VBT will be made that whatever covalent bond will be made what will happen? will overlap which orbital will overlap? those who will have unpaired electrons because electrons will be unpaired and when they will come then they will pair and bond will be made from that paired electron so overlap of half filled valence shell orbitals of bonding Atoms, okay, this is unbounded state.

This is bonded state one man And now so no this overlap allows electrons with opposite spins from each atom to pair up only valence orbitals having Unpaired electrons will participate in the bonding liquid line only only valence write what I have to write only valence oh bro he said it in anger ok write only you have written the whole ok write write the first important point of this theory only valence only valence orbital having unpaired electrons only valence orbitals having unpaired electrons will valence orbitals having unpaired electrons will overlap to form a covalent bond. This is the first principle. having unpaired electrons will overlap to form a bond with opposite spins with opposite spins with opposite spins this was the main point which came out of this theory ok now we will move ahead why pairing happens?

so that what can that system do to its energy? we have already discussed this next then when orbital overlap will happen then it will be like that efficient If there is an effective overlap, then what will be the strength of the bond? Increase. If there is a non-efficient overlap, then what will be there?

Strength will be reduced. This is the next principle of our BBT theory. The more the extent of overlapping, the stronger the bond will be.

The more the overlapping will be non-efficient, we will discuss further. how it will become efficient and how it can become non-efficient ok now if there is effective overlap then what will happen now the condition of effective overlap is if direction orientation of sub-orbital is correct then effective overlap will happen if their direction is not correct then a non-effective overlap will be made like an example I will explain from here see in this, in this the overlap of this orbital is effective overlap when one bond is formed then this orbital is in standing position vertical position, vertical position when this bond is formed, now this carbon atom can't proceed further when carbon atom can't proceed further then the orientation of these orbitals is only this Okay? so now if their interaction is also there then what kind of interaction will be there? weak interaction how will it be? that's why this bond will be called sigma in the future and this bond will be called pi bond pi bond is a weaker bond sigma bond is a stronger bond why did I tell this?

for now I had to tell the orientation factor I had to tell the orientation factor that when the orbital will come head to head see, then the talks starts when orbital will come head to head will come in front of us then what will we say? overlap is going on with good orientation but after overlap now a situation is created for inorbital now an orientation is not like good because now this carbon is not going forward so now how is their orientation? non effective overlap but still there is an overlap how is the overlap?

how this overlap is shown in many books I will show you this in many books you will see this overlap like this this is something like that the lobe was above this lobe this lobe of p-orbital what has happened? these orbitals have been bent what has happened? a little bit because this is not fixed how is this?

like if you hold a balloon in your hand, then what happens to the balloon? it keeps on moving here and there you can understand these lobes of p orbital in this way it is just a way of representation someone does it like this, someone writes like this and makes a line understood the point? but both are the same type of bonds PP overlap How is it?

There are overlaps of p-p orbital and the pi bond has formed and what are the electrons in the pi bond? pi electrons and those who are in the sigma bond, we will call them sigma electrons Okay? Did you understand this much? Okay, fine In the same way, now see p-p overlap, you understood this Now there are three types of p orbitals px, py, pz one participant must have done here for now understand that done how many are left? two so one p orbital will be like this here perpendicular lie on the other axis also one will be like this and one will be like this so the other p orbitals will be one bond is made like this the other will be seen in another color how it is seen?

here it is and its electron is visible here see from the other angle, it is here means what are two electrons doing in it? they are rotating continuously, they are present now they don't know where they are they can be here or there but their zone is this right, that's why we call it switching we are making it with a pen again and again this thing we want to say that the two electrons are switching here and here again and again This is same. This switching and this switching.

These are the two electrons which we are showing here and here. It is just a representation of this one. That means electron is here, here.

So it is like this. In pi bond electrons are like this. And how will the other ones be in pi bond? Like this. Right?

Weak overlap. But... Existing now is he go kiss the rickety-goo. Sorry sense me.

I said it. I think you be way you think of the career We check a club era a club aura a key era a key era So you be pi bond hair or the a douche wrap I bond hair or beach McConaughey Sigma so orientation good orientation axial overlap effective overlap strong bond weak overlap then weak bond, pi bond formation so what was the concept of VBT if the extent of overlapping is good but with orientation then good bond will be formed means strength of the bond will increase if overlap is good but orientation is not good then overlap bonding strength of the bond will be weak That's all for today. Okay.

That's all for today. Let's take it. Sit down.

Why are you waiting? Who teaches Maths, sir? Sir, Linka.

Do you want to make a show in his class? No? Keep quiet, sir.

You are useless. The one who gets the attendance can go. Okay. Aparajit.

Arvind. Shyamla. Ashlesha. Bishwaranjan.

Gargi. Ghanat. Jayakrishna. Kaliprasad. Madhusmita.

Megha. Monali. Om Prakash.

Om. Preeti Priyanshu Rajat Rupesh Rupesh saishritam stanvi say on Shruti Shivangi so hun so hun shri hun Swayam Swayam Yashashri Divyanshu Anushka Abhishek Ayush Ritesh Ayush Swayam Pratyusha Sudipth Zinit Bignesh, Neel, Himanshu, Jignyasha, go go whoever has done it, Shubhankar, Subham, Deeptanshu, I will put it son, go you guys, Adyasha, Ayush, Rosalina. udvashi swapnali namrata sahiprasad aditya riyazuddin dvjyoti priyani ekta krishna anushka sri anshu

Transcript for:Chemical Bonding Overview

Transcript for:
Chemical Bonding Overview