Understanding Chemical Bonding Concepts

hey all welcome to homeschool hope everybody are doing good and today I have come up with the chapter chemical bonding already two videos are over on chemical bonding where I discussed about cobalt bond formation, octet rule, limitations of octet rule and I taught you a very very important and a very simple trick to write the Lewis structures of compounds easily. So don't miss it out. It was in part 1 of chemical bonding chapter. Coming to part 2, I taught you about ionic bond formation and we have discussed about the lattice enthalpy, how lattice enthalpy plays a major role in deciding the stability of ionic compound, right? All that is over. Coming to today's concept. it is the most important and interesting concept this is very much essential if you are preparing for any competitive examinations like NEET, JEE, CET whatever it is so pay at most concentration and listen to a topic carefully watch the video till the end definitely all your doubts regarding this concept will get clear so what is the concept The concept is studying about the phasin's rule and learning about the dipole moment. So coming to a topic, in our previous videos, we have discussed how ionic bonds can be formed. So just a small recap here. If you have an atom A, if it loses electron, it becomes cation. Cation. and the atom B on gaining electrons it becomes anion. So what happens A plus B minus will come near, they stay together and an attraction gets created between A plus ion and B. B minus ion and we call that bond as ionic bond. It is ionic bond, right? Okay. And we have also studied how covalent bonds are formed. See, covalent bonds are, formed by sharing of electrons. You have hydrogen. You also have chlorine. Hydrogen has one electron. Chlorine in its outermost shell, you will find seven electron, right? So what happens here? Sharing of these two electrons takes place between hydrogen and chlorine and this leads to the formation of covalent bond between hydrogen and chlorine. So this is how our covalent bonds will form. Right? So in general if I have to revise, ionic bonds are formed by transfer of electrons. Transfer of electrons. And covalent bonds are formed by sharing of electrons. So all that we have already discussed. Right? Okay. And now what I am going to tell you is every, points are very very important, note it down. Every ionic bond, every ionic bond has certain amount of covalent character. Okay. So no bond is 100% ionic. So you will not have a bond 100% ionic here. Some covalent character you will observe in ionic bond. Right. So every ionic bond has some covalent character. Covalent character. So how much of covalent character can be present? Say for example you have NaCl. NaCl. Normally we say between Na and Cl there is ionic bond but this bond is not 100% ionic. Some amount of covalent nature is there. So how do you decide that covalent nature of ionic bond? How do you find how much extent covalent nature is there in this particular ionic compound? Or if you want to compare say you have sodium chloride you have cesium chloride they Right? So sodium chloride is ionic compound, cesium chloride is also ionic. Both are ionic. Right? But in which of the compound covalent character is more? I told you in every ionic compound little of covalent character you will observe. So here both are ionic compound. Both have ionic bonds. I said covalent character is observed. Here covalent character is observed. Here though it is ionic bond, little covalent character is observed. But in which case more covalent nature is there. So how do you decide that? That is decided by a concept of polarization. Okay. So this ionic nature, this ionic Sorry, this covalent nature, covalent nature of ionic bond, of ionic bond is studied by a concept. Okay, studied with the help of, it can be understood in a better way with the help of, with the help of a concept called polarization. polarization. Okay, so here polarization, you know, for polarization, there are certain conditions. So, those conditions we will study as a rule called Fasen's rule. Fasen's rule right. So when do you study this Fasen's rule? Fasen's rules are related to a concept called polarization okay. So what is polarization? With this polarization concept you can understand about covalent character of ionic bond in a better way. Right? So hope you understood why we have to study this Fasen's rule and what is the use of Fasen's rule. Okay, so similarly, Every covalent compound has some ionic nature. Okay. Say bond between hydrogen and chlorine is covalent bond. But some amount of ionic nature is there. Ionic character is there. Okay. So that is studied by a concept of dipole movement. Okay. So what I can write here is every covalent bond. covalent bond has ionic character ionic character okay so that ionic character is studied by this ionic character is studied by what concept studied with the help of a concept dipole moment. So dipole moment is the concept with which we can understand to how much extent ionic character is there in a particular covalent bond. Okay and polarization is the concept or Fasen's rule is the concept that we study to understand how much covalent character is there in ionic bond. Okay, so this is how we have to now focus on two concepts. One is polarization, the other one is dipole moment. First, let us learn about the concept of polarization. That means using which we can understand the covalent character of ionic bond. Okay, so let's solve these types of questions. Say if two ionic compounds are given, so which of them are the covalent compounds? you know have more covalent character which has less covalent character. You know all these types of questions can be solved very easily if you know Fasson's rule, if you know the concept of polarization. So let's quickly go for the concept of polarizations or Fasson's rule. Observe what happens normally here. Say as I already told you polarization means learning covalent character in ionic compound. You can look at the definition. The distortion of electron cloud of anion by cation is what called as polarization. So what do you understand by this sentence? It's very simple. Suppose if this is our cation and this is our anion, right? See, you know what? Every cation has a nucleus around that electrons are there and every anion will have a nucleus around that electron cloud is there. See in case of anion more number of electrons so I can say more electron cloud. Electron cloud in the sense what? The area where electrons are more. Okay so anion has more electron cloud. So electron density is more around the anion, right? More number of electrons. Fine. Say when they come near, you know, this is our cation. Now anion is coming near because to form an ionic bond, you know, both of them should be near, right? So when this anion comes near, what happens is the positive. charge of cation will try to pull the electron cloud towards itself. Okay, actually speaking, what can happen here is nucleus, nucleus of cation is very strong. It is highly positive in nature, right? So nucleus of cation, what happens? Pulls, pulls the electron cloud of anion out. towards itself towards itself right so that itself we will call it as polarization so positive charge of nucleus is very strong in cation okay so this guy it will see the electron cloud since there is an attraction between positive and negative you know what electron cloud will tend to move more towards you know this is a cation stays as it is but electron cloud you see it is slightly moving towards positive charge. Okay, so here deviation of ionic character took place. okay so the electron cloud is moving more towards positive side okay so it's like the electron cloud is shared between positive and negative guy here so if anything is shared between the ions or atoms we call it as covalent character isn't it see cations positive charge is very strong that it is attracting you know the electron cloud of anion. Distortion in the sense what? The electron cloud of anion is moving. It is distorted. It is getting deviated towards the positive cation. Due to this distortion you know ionic character got deviated. Slightly covalent character is seen in a compound. Okay, so this is what this is what we call it as polarization. So this kind of distortion is called polarization. So once you observe the polarization, you know, here the electron cloud is getting shared between this positive guy and negative guy. So more the polarization, we say more is the covalent character. Okay, clear. So, hope you understood what do you mean by polarization. It is the distortion that is moment of electron cloud of an ion by cation. Okay, who is responsible for this distortion? It is the cation. Right? So, here our polarization. I can write polarization is directly proportional to covalent character, right? So, more the polarization, more the distortion you find, more is the covalent character, right? So, and this polarization is universally proportional to ionic character. When you find more of these, you can write more of these. polarization ionic character is very very least okay so that point also i can write here polarization is inversely proportional to ionic character or ionic nature okay if covalent character is more ionic nature will be less okay if ionic nature is more covalent character will be right. So, that way. So, more the distortion you find, more the pull of electron cloud you find, then you know more is the covalent character you will observe. So, this is the reason behind why ionic bond has some amount of covalent character. Okay fine. So here we will try to understand the meaning of certain words right. So there is a word called you know polarizing power. Polarizing power. So what do you mean by polarizing power? It is the ability of cation to pull the electron cloud towards itself. The cation must be more active. So if this guy is more active, then only it can pull the electron cloud towards itself. So how much extent it is active, how much capacity it has to pull the electron cloud towards itself. So that capacity of cation is called polarizing power. Okay, so what I can write here, ability, ability of cation, cation to pull, to pull the electron cloud of anion towards itself. is called polarizing power of cation. Okay, so is called polarizing power of power of cation. Okay, so this is the meaning of the word polarizing power. So, polarizing power is the capacity of cation. With respect to cation, we will talk. Okay, so how much is the cation is capable of pulling that electron cloud towards itself. So, that capacity of cation is spoken in terms of, you know, polarizing power. And coming to another term that we have to concentrate that is polarizing power, polarizability. Polarizability. So, what do you mean by polarizability? Polarizing power is something related to cation and polarizability is something related to anion. Okay. See to how much extent the electron cloud is going. So, if this guy is pulling, this guy must go. go no only then the distortion takes place right. So the capacity of anion to go towards cation is called polarizability of anion okay. So what is polarizability? Ability of electron cloud of anion anion to go towards this. to go towards cation. I am telling all this with the very simple words so that you can understand. So you can copy these definitions in your book. So polarizability is the ability of anion to go two words cation is called you know polarizability okay so the meaning of these two words are very very important so if a ionic compound has more polarization we say that ionic compound compound has more covalent character. Then actually there are certain conditions for polarization. Polarization can be observed in a better way if these conditions are satisfied. Those conditions or rules for polarization is called Fasen's rule. So let us understand the rules of Fasen's. See there are three rules that you have to concentrate, three Fasen's rule. So Farzen's rule why we are studying? For learning effective polarization okay. So when do we decide that the polarization is maximum? You know to understand that we have some conditions and rules you know. So those rules are our Farzen's rule okay. Learning for effective polarization. Fine, look at the first rule that I have written on a board. Cation should be small, anion should be big. Okay, see any ionic bond is formed with cation and anion, right? Whenever cation is... very small, anion is very big then the polarization this distortion of you know anion will be maximum okay so that is what the meaning of first rule. Cation must be very very small anion must be very very big in other words I can say that there should be a large difference in size. There should be a large difference in size. There should not be a comparable sizes. Okay. So anion too much big, cation too much small. Then you will observe more distortion that is more polarization, more covalent character. So to observe more covalent character in ionic bond, cation should be very very small, anion must be very very big. Right. Very very important condition guys. Coming to second one. Both cation and anion should have high charge. Okay. See cations can have a charge. It can have plus 1, it can have plus 2, it can have plus 3. So it is better if cation has high charge. Suppose you have two compounds. One is CuCl, other one is CuCl2. Okay. If I ask you among CuCl and CuCl2, which one is more covalent? Both are actually ionic compounds, right? So they have some covalent character. Both have more covalent character only, actually speaking. But among them, which one has more covalent character? So how do you decide? Check based on the charge. Here the copper's charge is plus 1. Here the copper's charge is plus 2. So more the charge, more is the covalent nature. okay so this works out for both cation and anion anion case minus 1 minus 2 minus 3 so more the charge more is the polarizing power okay so to observe better polarization you know both cation and anion should have high charges right coming to last point this is very very important to understand You will observe better polarization when cations have pseudo inert configuration. So what do you mean by the word pseudo inert configuration? The meaning of the word pseudo means false, right? See, based on this point, I can divide cations into three categories actually. Cations, cations with inert electronic configuration, inert TC means electronic configuration. Okay, see Na plus, Mg plus 2, these are examples. Say Na plus, you see here, Na plus what is its electronic configuration? 1s2, 2s2, 2p6, right? So, this is the electronic configuration of inert gas that is neon, right? So, here plus has exact inert gas electronic configuration. This is electronic configuration of neon. So, Na plus is actually showing exact electronic configuration as that of neon. So, that is why Na plus is called cation with inert electronic configuration. Inert, not pseudo. Inert, exact. Na plus electronic configuration is exactly similar to inert gas. So, I call Na plus as cation with exact inert gas electronic configuration. Okay. Say likewise, Mg plus 2. Exact inert gas electronic configuration it will show. Right. So, Na plus, Mg plus 2, Al plus 3, Al plus 3. All of them come under cation with inert electronic configuration. Okay. And the other type of cation you see. Cation with non-inert. electronic configuration, okay. Say lead, if you take up lead ion, you know, it will not show, you know, inert gas electronic configuration, right. So, such cations are called non-inert electronic configuration showing cations, right. And coming to third category which is very important, cations with pseudo inert pseudo inert electronic configuration example for this is Zn plus 2 Cu plus Ag plus okay so all of them will come cadmium okay so cadmium plus 2 will come you know all these d block elements specially zinc plus 2 Cu plus 2 Ag plus 2 Cd plus 2 all of them will come. So let me tell you what is this pseudo inert electronic configuration. So observe the ion Zn plus 2. Okay, first let me write only zinc. What is its electronic configuration? Its electronic configuration is argon till 80. See its atomic number is 30 till 18. You know, it's the electronic configuration of argon and later you will have 3s2, 3p6, 4s2. Okay, 3d10. Okay, Zn plus 2 electronic configuration is how much? Argon 3s2 3p6 these electrons last shell means fourth shell. So, in this shell 2 electrons if it loses it becomes Zn plus 2. So, its electronic configuration is 3d10. So, this is not same as any noble gas electronic configuration this electronic configuration is not similar as any noble gas electronic configuration but this is stable only this is stable itself you see all orbitals are completely filled s orbital with two electron p orbital with six three orbital with ten that means our third shell is completely filled with 18 electron okay so our third shell is completely filled with 18 electron it is completely stable but electronic configuration is not similar electric configuration is stable right but not similar to but not similar to Any noble gas, any inert gas, right? So, such a configuration, electronic configuration is called pseudo inert electronic configuration. Okay. So, usually try to remember Zn plus 2, copper plus, Cu plus, Ag plus, Cd plus 2, all these cations if they are there in a compound, they will show more polarizing. polarization okay they will have more polarizing power so that's why those compounds will have more covalent character okay so these three points are very very important to understand okay say for example question can be asked this way now let us work it out with few questions so that you will get a clarity what actually i'm talking about look at the first question you have cu cl and NaCl. Okay, so my question is which has more covalent character? Which has more covalent character? Okay, so this is the question. So how do you decide? Copper chloride Na plus. Here copper's charge is plus 1, Na's charge is also plus 1. Okay. So based on the charge you can't decide. And cation should be small, anion should be weak right. So normally bigger cation say compared to copper sodium comes in the first group. So you know this sodium is comparatively big cation. Actually speaking this is cation. cation which is big whereas this cation This cation is actually small. Okay. So this is the small cation and this is the big cation. What did the point says? Cation should be small, anion should be big. So anion is common in both the compounds. Whereas cation, copper is small, sodium is big. So we can say copper chloride. Copper chloride is more covalent. Isn't it? Because compared to sodium, copper is smaller cation. Sodium is big. We know first group elements are bigger, right? And that is one point you can concentrate. Then the other point, looking at this copper, what is copper? Copper is cation with pseudo inert electronic configuration. What is our answer? Third point says cations with pseudo inert configuration have high polarizing power. High polarizing power, high polarization. High polarization, more covalent character. Isn't it? So based on this point also whenever you find these cations definitely they have more covalent character because all these cations will come under the cations with pseudo electronic configuration. So one is size is small the other reason is what this particular copper has pseudo, pseudo inert. electronic configuration. So that is why you know this copper chloride has more covalent character. Clear? So this is how you can decide like among a given compounds which one is more covalent and which one is less covalent. So this is one important type of question for your competitive examinations. So you have to be very very careful. And coming to the next question, So second question for this you are giving answer in a comment section. So please try this. You have KCL and you also have AGCL. So tell me which one has more covalent character. My question is which one has more. Covalent character. Okay. So just based on the concept decide your answer. Clear? Fine. And another question. Question number 3 also try to give answer. KCl, NaCl. Okay. So here you are telling me which one is more ionic. Which one is more ionic. Okay. So based on the Farzen's rule, you can work on with these questions. So two questions I asked you. One is this KCl and AgCl. Among them, which one is more? Covalent which has more covalent character. Second question is KCl and NaCl and tell me which is more ionic. Don't forget to post your answer in the comment section. Let me know who is answering first. Okay. So that is all about covalent character in ionic compound. I mean entire things about polarization. Okay. And now we will go for other aspect. So now every covalent compound has ionic character, isn't it? So how do we decide that ionic character? You know, that is with the help of a concept called dipole moment. So let us understand everything about dipole moment. See guys, this dipole moment is also one of the very, very important concept that you have to concentrate. So as I have already explained you, dipole moment will help you to... decide ionic character in covalent bond. So let us understand what actually we mean by this dipole moment and how do we find this dipole moment. Okay, so let me take a covalent compound HCl. Okay, so it has a covalent bond between hydrogen and chlorine. This covalent bond which means the presence of two electrons exactly in between hydrogen and Cl. But there is electronegativity difference between hydrogen and Cl. Right? So there is... There is... High, high electronegativity difference, electronegativity difference between hydrogen and Cl. So Cl is more electronegative here. So this has a ability of pulling this bond towards itself, right? So what happens? This bonding. slightly moved more towards Cl. This moving of bond towards Cl creates, so this particular concept creates dipole, creates dipole in a molecule. So what do you mean by dipole? Dipole in the sense charge creation. See when a bond is slightly moved more towards Cl, Cl will have a slightly negative charge. Hydrogen will gain a slightly positive charge. That means see in a bond there was hydrogen's electrons. Now it is not completely belong to hydrogen. It is not even shared. You know that shared electron was moved more towards Cl. It's like hydrogen have lost that electron. Not completely lost, slightly it is losing its electron, right? So, that's why a slight positive charge on hydrogen, okay? So, this delta meaning in chemistry is slightly positive. Whenever we write delta positive, it means hydrogen is not completely positive. It has not completely lost electron. It is in a, you know... deficiency of electron it is having a deficiency of electron slight deficiency of electron so that is indicated with this sign slightly positive and this we call it as slightly negative okay so it has not completely took the electron of hydrogen just the bond is slightly moved towards Cl because this is more electronegative so bond will always move towards the atom which is more electronegative. So why the bond has moved towards Cl? Because electronegativity of Cl is more than electronegativity of hydrogen. So that is the reason bond has moved towards here. So this this charge creation, slight charge creation in a molecule is called dipole. That's why we say ionic. So this is what ionic character, right? So it's like a positive part is there, negative part is there in a compound, right? Slightly positive, slightly negative. This is what we say ionic character generation in a covalent bond. That's what we mean by dipole. Dipole means what? Observing this slight charge generation, charges in a molecule is called dipole. Okay. So you will observe dipole only when there is a high electronegativity difference between the two atoms. Okay. So this is how ionic character is observed even in a covalent bond. And now the strength of dipole, the strength of dipole. is measured is measured by a concept called dipole moment okay so what is dipole moment dipole moment is used to measure the strength how extent the charges have been developed in the molecule you know if the charge on two two atoms is more then we say more ionic character is there in a covalent bond right so the the strength of this charge formation strength of dipole in other words is always measured by dipole moment which has a symbol nu okay so if i have to give the definition of dipole moment it is nothing but you know the product of it is the product of charge you charge and distance between the two atoms. So that means say this is what the formula we write nu is equal to charge Q into D. So what is Q here? Q is nothing but charge of ion I mean charge of atoms and d is distance between the atoms. So distance between the atoms is nothing but what? Bond length right? That's what we can also call it as bond length. Bond length is the distance between the two atoms you know this distance we will call it as bond length. So charge into bond length or distance if you do you will get the value for nu that is dipole moment. Looking at the value, you can say whether a compound has more ionic character or less ionic character. More the dipole moment, more ionic character is there in a covalent compound. So, how do you decide? More. If you have more nu, then more is ionic character. right so this is what you need to understand and few more things let's let's come to the unit of mu here so you should have an awareness about units of dipole moment that is new in si system that is in mks system the unit is coulomb meter okay c for coulomb charge You know, charge unit is coulomb and distance, it is like bond length is nothing but distance unit is meter, right? So, coulomb meter is the unit. In CGS system, the unit is ESU into meter, ESU, electrostatic force is called as ESU, ESU into meters, okay? So, and dipole moment has another unit, another unit. Okay, which we famously call it as Dubai. Debye which is represented as D. Okay. So, here you need to understand 1 Debye is equal to 0.33 into 10 power minus 24 coulomb meter. Coulomb meter. It is not centimeter. It is coulomb meter. Okay. Or 1 Debye is equal to 10 power minus 18 EFU. into centimeter. Okay. So, one device value is this much in coulomb meter units and one device is this much in ESU centimeter unit. Sorry, here it should come centimeter, right, in CGS system. So, these are the units of, you know, dipole. moment okay so the most important unit is debi debi is just a unit okay so one debi is this much coulometer and one debi is this much esu centimeter so this this is what you need to understand and now you know we can actually calculate the percentage ionic character that is there in covalent compound so take down that formula percentage ionic character if you want to find out you percentage ionic character in any covalent compound the formula is observed observed dipole moment divided by calculated dipole moment into 100 okay so this formula is very very important guys so percentage to how much percent ionic character is there in a particular compound that if you want to calculate The formula is this observed dipole moment divided by observed dipole moment divided by calculated dipole moment into 100. So now we will see one problem where we can apply this formula so that you will get an idea how actually we calculate dipole moment. So what is the major formula of dipole moment? It is the charge into bond length that is the distance between the two atoms. So these are the various units and this is how we can calculate percentage ionic character. Let us see one problem here. See this problem guys dipole moment of HCl is 1.03 d that means it is a observed dipole moment they have given 1.03 d. Bond length of HCl they have given that is D they have given 1.27 angstrom. Calculate percentage ionic character. What is the formula? Here we have observed U, observed dipole moment divided by calculated dipole moment into 100. Observed dipole moment they gave. We have to calculate calculated dipole moment right. So how do you calculate dipole moment? It is charge into dipole distance isn't it so what is the charge here in esu centimeter let us calculate mu in esu centimeter units i'm calculating so charge value in esu centimeter is how much 4.8 into 10 power minus 10 okay so uh charge we know charge of an electron is how much one unit charge one unit Charge value is how much? 1.6 into 10 power minus 19 coulomb. It is in coulomb. But in electrostatic units, its value is 4.8 into 10 power minus 10 ESU we say. Okay. So, in ESU, charge value is this much. In coulombs, charge value is this much. So, I am calculating, you know, the new value in ESU centimeter. So, I took charge value in this units 4.8 into 10 power minus 10 into distance. Distance I need to take it in centimeter. So, we all know 1 angstrom is equal to 10 power minus 10 meter which is equal to 10 power minus 8 centimeter right. So, how much 1.27 into 10 power minus 8 centimeter. So, what is the new value you will get here? 6.10 into 10 power minus 18. 10 power minus 10 into 10 power minus 8 is 10 power minus 18 ESU centimeter. And convert this into the unit. It is 6.10 into 10 power minus 18 divided by 10 power. See, if you want to convert this into a unit, you will have to convert this into a unit. Oh, one debate in... You know CGS from CGS units to 1 to pi it is 1 to pi is equal to 10 power minus 18 ESU centimeter right. So I will divide by 10 power minus 18 this gets cancelled. So new value is 6.10 the pi. Okay what is this dipole moment? This is actually our calculated dipole moment. So now you have observed dipole moment that is given in a question. This is our calculated dipole moment. So use the formula and find out. So post your answer in comment section. Okay. So calculate post the percentage ionic character that is there in HCl bond. Right. So this is how we can calculate dipole moment. See guys, using dipole moment, we can decide the shape of these covalent molecules or from knowing the structure of covalent molecule, we can say whether dipole moment is there or not. Okay, so that's what we will try to learn now. You know, identifying dipole moment from structure. So, what I am dealing is identifying the covalent molecules. Dipole moment from structure of molecules. So this is also very very important thing one must understand. First thing you need to learn is your dipole moment is vector quantity. So we know the properties of vectors, right? So vector quantity, it will be mentioned with the help of arrow mark. Dipole moment is mentioned with the help of, you know, dipole. Especially, I am not the dipole moment. Dipole. in a molecule can be represented with the help of arrow mark. Okay. So you have to show arrow mark from positive atom to negative atom. Okay. For example, you see carbon dioxide. Carbon dioxide has a linear structure. How do you know that carbon dioxide has a linear structure? You will understand this in VSEPR theory that you will study next. Okay. So just as of now, you will know that carbon dioxide has a linear structure. Okay. So you will know that carbon This is the structure of your carbon dioxide. And I want to decide whether carbon dioxide shows dipole moment or not. okay so if dipole moment is there then we say this particular compound has you know ionic character if dipole moment is not there then we say this will not have ionic character okay so how do you decide you see this is a positive part this is a negative part so how will you show the dipole it's a vector quantity say dipole will always move from positive to negative side so this is a vector And this here also dipole you will observe. Oxygen is electronegative. Carbon is electropositive. So this is the dipole you will show. And vector quantity in opposite direction will get cancelled right. So what is the dipole moment here? Dipole moment is 0. Okay. So I say this particular molecule is not having any ionic character. Okay. So this is how from structure you can decide whether dipole moment is there or not. okay fine and you know another molecule let me take BF3 so if I have to write the structure of BF3 it is planar it is planar And how will you show the dipoles here? This is positive, this is electronegative. So here the dipole is always from positive side to negative side. That's how you have to show the dipole. Okay, from understanding dipoles, dipole is a vector quantity. By understanding this dipole or these vectors, you can decide whether dipole moment is shown by a compound or not. And this bond, how will you, for this bond, how will you show the dipole? Positive, negative. So, dipole you have to show this way. For this bond, how will you show the dipole? Positive, negative. So, dipole is this way. And it is planar, okay? So, for planar and this is how the dipoles are, okay? So, all in different directions and the molecule is highly planar. So, here also dipole moment will be zero. Remember, for any planar molecule, the dipole moment will be 0. Okay, fine. Now coming to very very important example, I will compare the dipole moment of NH3 and NF3. So if I ask you which has got more dipole moment among these two, which has got more dipole moment, then you can decide based on their structures. Okay, so what is the structure of NH3? Structure of NH3 is pyramidal, right? H H, H and there is a lone pair. This is and how do you decide that this is a structure and this is how we will write? It is based on the Vesper theory. Hold on. About Vesper theory we will discuss in our next class. Okay. So this is NH3 structure. Okay. And NF3, and a lone pair. Okay. So how will you show a dipole for this bond? Nitrogen, more negative, electro negative, hydrogen, electro positive. Positive to negative you have to show the arrow mark. I mean vector. Okay. And how will you show the dipole? For every bond you have to show the dipole. From the direction you are deciding whether it will show dipole moment or not. Okay. So NH bond. How will you show the dipole? Like this. NH bond, dipole like this. And nitrogen, and lone pair between nitrogen and lone pair lone pair is more negative so dipole is like this see all arrows are moving in a same direction say the resultant vector is very much strong right so you must know some basic properties of vectors here okay so when all these vectors are moving and joining at a single point the resultant vector is very strong so here Dipole moment is high. Dipole moment is very much high. Okay. So very high. Very high. Because the resultant vector is very very strong. Right. Okay. And coming to NF3. So how will you show the dipoles for a bond? Compared to nitrogen, fluorine is more electronegative. So the dipole is like this. And for this bond, dipole is like this. For this bond, dipole you will show like this. And here between nitrogen and lone pair. Lone pair is more negative. So, dipole you will show up. And here you see one arrow direction will get cancelled with another arrows direction, right? So, if you take this above arrow and any one below arrow, they will get cancelled, right? So, the resultant dipole is due to only two arrows. The resultant dipole is due to only any two bottom arrows, okay? So that's why here you will observe dipole moment but the dipole is less. Dipole is less. See the moment you see here you would think that NF3 has got greatest dipole moment because you know electronegative elements are 3 right. Fluorines are 3 but no NH3 has got more dipole moment that has decided by structure. Okay so to some extent. extent these structures will tell you whether a molecule has greater dipole moment or lesser dipole moment okay so looking at the structure you can able to decide which has got more and which has got less dipole moment so let me meet you all in the next video with more examples of dipole moment and let me discuss all bond parameters thank you so much take care and keep revising

All that is over. Coming to today's concept. it is the most important and interesting concept this is very much essential if you are preparing for any competitive examinations like NEET, JEE, CET whatever it is so pay at most concentration and listen to a topic carefully watch the video till the end definitely all your doubts regarding this concept will get clear so what is the concept The concept is studying about the phasin's rule and learning about the dipole moment. So coming to a topic, in our previous videos, we have discussed how ionic bonds can be formed.

So just a small recap here. If you have an atom A, if it loses electron, it becomes cation. Cation. and the atom B on gaining electrons it becomes anion.

So what happens A plus B minus will come near, they stay together and an attraction gets created between A plus ion and B. B minus ion and we call that bond as ionic bond. It is ionic bond, right?

Okay. And we have also studied how covalent bonds are formed. See, covalent bonds are, formed by sharing of electrons. You have hydrogen. You also have chlorine.

Hydrogen has one electron. Chlorine in its outermost shell, you will find seven electron, right? So what happens here? Sharing of these two electrons takes place between hydrogen and chlorine and this leads to the formation of covalent bond between hydrogen and chlorine.

So this is how our covalent bonds will form. Right? So in general if I have to revise, ionic bonds are formed by transfer of electrons.

Transfer of electrons. And covalent bonds are formed by sharing of electrons. So all that we have already discussed.

Right? Okay. And now what I am going to tell you is every, points are very very important, note it down.

Every ionic bond, every ionic bond has certain amount of covalent character. Okay. So no bond is 100% ionic.

So you will not have a bond 100% ionic here. Some covalent character you will observe in ionic bond. Right.

So every ionic bond has some covalent character. Covalent character. So how much of covalent character can be present?

Say for example you have NaCl. NaCl. Normally we say between Na and Cl there is ionic bond but this bond is not 100% ionic.

Some amount of covalent nature is there. So how do you decide that covalent nature of ionic bond? How do you find how much extent covalent nature is there in this particular ionic compound? Or if you want to compare say you have sodium chloride you have cesium chloride they Right?

So sodium chloride is ionic compound, cesium chloride is also ionic. Both are ionic. Right? But in which of the compound covalent character is more?

I told you in every ionic compound little of covalent character you will observe. So here both are ionic compound. Both have ionic bonds. I said covalent character is observed. Here covalent character is observed.

Here though it is ionic bond, little covalent character is observed. But in which case more covalent nature is there. So how do you decide that? That is decided by a concept of polarization. Okay.

So this ionic nature, this ionic Sorry, this covalent nature, covalent nature of ionic bond, of ionic bond is studied by a concept. Okay, studied with the help of, it can be understood in a better way with the help of, with the help of a concept called polarization. polarization. Okay, so here polarization, you know, for polarization, there are certain conditions.

So, those conditions we will study as a rule called Fasen's rule. Fasen's rule right. So when do you study this Fasen's rule? Fasen's rules are related to a concept called polarization okay.

So what is polarization? With this polarization concept you can understand about covalent character of ionic bond in a better way. Right?

So hope you understood why we have to study this Fasen's rule and what is the use of Fasen's rule. Okay, so similarly, Every covalent compound has some ionic nature. Okay.

Say bond between hydrogen and chlorine is covalent bond. But some amount of ionic nature is there. Ionic character is there.

Okay. So that is studied by a concept of dipole movement. Okay.

So what I can write here is every covalent bond. covalent bond has ionic character ionic character okay so that ionic character is studied by this ionic character is studied by what concept studied with the help of a concept dipole moment. So dipole moment is the concept with which we can understand to how much extent ionic character is there in a particular covalent bond. Okay and polarization is the concept or Fasen's rule is the concept that we study to understand how much covalent character is there in ionic bond.

Okay, so this is how we have to now focus on two concepts. One is polarization, the other one is dipole moment. First, let us learn about the concept of polarization.

That means using which we can understand the covalent character of ionic bond. Okay, so let's solve these types of questions. Say if two ionic compounds are given, so which of them are the covalent compounds?

you know have more covalent character which has less covalent character. You know all these types of questions can be solved very easily if you know Fasson's rule, if you know the concept of polarization. So let's quickly go for the concept of polarizations or Fasson's rule. Observe what happens normally here.

Say as I already told you polarization means learning covalent character in ionic compound. You can look at the definition. The distortion of electron cloud of anion by cation is what called as polarization. So what do you understand by this sentence?

It's very simple. Suppose if this is our cation and this is our anion, right? See, you know what?

Every cation has a nucleus around that electrons are there and every anion will have a nucleus around that electron cloud is there. See in case of anion more number of electrons so I can say more electron cloud. Electron cloud in the sense what? The area where electrons are more.

Okay so anion has more electron cloud. So electron density is more around the anion, right? More number of electrons.

Fine. Say when they come near, you know, this is our cation. Now anion is coming near because to form an ionic bond, you know, both of them should be near, right?

So when this anion comes near, what happens is the positive. charge of cation will try to pull the electron cloud towards itself. Okay, actually speaking, what can happen here is nucleus, nucleus of cation is very strong. It is highly positive in nature, right? So nucleus of cation, what happens?

Pulls, pulls the electron cloud of anion out. towards itself towards itself right so that itself we will call it as polarization so positive charge of nucleus is very strong in cation okay so this guy it will see the electron cloud since there is an attraction between positive and negative you know what electron cloud will tend to move more towards you know this is a cation stays as it is but electron cloud you see it is slightly moving towards positive charge. Okay, so here deviation of ionic character took place. okay so the electron cloud is moving more towards positive side okay so it's like the electron cloud is shared between positive and negative guy here so if anything is shared between the ions or atoms we call it as covalent character isn't it see cations positive charge is very strong that it is attracting you know the electron cloud of anion. Distortion in the sense what?

The electron cloud of anion is moving. It is distorted. It is getting deviated towards the positive cation.

Due to this distortion you know ionic character got deviated. Slightly covalent character is seen in a compound. Okay, so this is what this is what we call it as polarization. So this kind of distortion is called polarization.

So once you observe the polarization, you know, here the electron cloud is getting shared between this positive guy and negative guy. So more the polarization, we say more is the covalent character. Okay, clear. So, hope you understood what do you mean by polarization.

It is the distortion that is moment of electron cloud of an ion by cation. Okay, who is responsible for this distortion? It is the cation.

Right? So, here our polarization. I can write polarization is directly proportional to covalent character, right? So, more the polarization, more the distortion you find, more is the covalent character, right? So, and this polarization is universally proportional to ionic character.

When you find more of these, you can write more of these. polarization ionic character is very very least okay so that point also i can write here polarization is inversely proportional to ionic character or ionic nature okay if covalent character is more ionic nature will be less okay if ionic nature is more covalent character will be right. So, that way.

So, more the distortion you find, more the pull of electron cloud you find, then you know more is the covalent character you will observe. So, this is the reason behind why ionic bond has some amount of covalent character. Okay fine. So here we will try to understand the meaning of certain words right. So there is a word called you know polarizing power.

Polarizing power. So what do you mean by polarizing power? It is the ability of cation to pull the electron cloud towards itself.

The cation must be more active. So if this guy is more active, then only it can pull the electron cloud towards itself. So how much extent it is active, how much capacity it has to pull the electron cloud towards itself.

So that capacity of cation is called polarizing power. Okay, so what I can write here, ability, ability of cation, cation to pull, to pull the electron cloud of anion towards itself. is called polarizing power of cation. Okay, so is called polarizing power of power of cation.

Okay, so this is the meaning of the word polarizing power. So, polarizing power is the capacity of cation. With respect to cation, we will talk. Okay, so how much is the cation is capable of pulling that electron cloud towards itself. So, that capacity of cation is spoken in terms of, you know, polarizing power.

And coming to another term that we have to concentrate that is polarizing power, polarizability. Polarizability. So, what do you mean by polarizability? Polarizing power is something related to cation and polarizability is something related to anion.

Okay. See to how much extent the electron cloud is going. So, if this guy is pulling, this guy must go.

go no only then the distortion takes place right. So the capacity of anion to go towards cation is called polarizability of anion okay. So what is polarizability?

Ability of electron cloud of anion anion to go towards this. to go towards cation. I am telling all this with the very simple words so that you can understand. So you can copy these definitions in your book.

So polarizability is the ability of anion to go two words cation is called you know polarizability okay so the meaning of these two words are very very important so if a ionic compound has more polarization we say that ionic compound compound has more covalent character. Then actually there are certain conditions for polarization. Polarization can be observed in a better way if these conditions are satisfied. Those conditions or rules for polarization is called Fasen's rule.

So let us understand the rules of Fasen's. See there are three rules that you have to concentrate, three Fasen's rule. So Farzen's rule why we are studying? For learning effective polarization okay.

So when do we decide that the polarization is maximum? You know to understand that we have some conditions and rules you know. So those rules are our Farzen's rule okay. Learning for effective polarization. Fine, look at the first rule that I have written on a board.

Cation should be small, anion should be big. Okay, see any ionic bond is formed with cation and anion, right? Whenever cation is... very small, anion is very big then the polarization this distortion of you know anion will be maximum okay so that is what the meaning of first rule. Cation must be very very small anion must be very very big in other words I can say that there should be a large difference in size.

There should be a large difference in size. There should not be a comparable sizes. Okay.

So anion too much big, cation too much small. Then you will observe more distortion that is more polarization, more covalent character. So to observe more covalent character in ionic bond, cation should be very very small, anion must be very very big. Right.

Very very important condition guys. Coming to second one. Both cation and anion should have high charge. Okay.

See cations can have a charge. It can have plus 1, it can have plus 2, it can have plus 3. So it is better if cation has high charge. Suppose you have two compounds.

One is CuCl, other one is CuCl2. Okay. If I ask you among CuCl and CuCl2, which one is more covalent? Both are actually ionic compounds, right? So they have some covalent character.

Both have more covalent character only, actually speaking. But among them, which one has more covalent character? So how do you decide?

Check based on the charge. Here the copper's charge is plus 1. Here the copper's charge is plus 2. So more the charge, more is the covalent nature. okay so this works out for both cation and anion anion case minus 1 minus 2 minus 3 so more the charge more is the polarizing power okay so to observe better polarization you know both cation and anion should have high charges right coming to last point this is very very important to understand You will observe better polarization when cations have pseudo inert configuration.

So what do you mean by the word pseudo inert configuration? The meaning of the word pseudo means false, right? See, based on this point, I can divide cations into three categories actually. Cations, cations with inert electronic configuration, inert TC means electronic configuration.

Okay, see Na plus, Mg plus 2, these are examples. Say Na plus, you see here, Na plus what is its electronic configuration? 1s2, 2s2, 2p6, right?

So, this is the electronic configuration of inert gas that is neon, right? So, here plus has exact inert gas electronic configuration. This is electronic configuration of neon.

So, Na plus is actually showing exact electronic configuration as that of neon. So, that is why Na plus is called cation with inert electronic configuration. Inert, not pseudo.

Inert, exact. Na plus electronic configuration is exactly similar to inert gas. So, I call Na plus as cation with exact inert gas electronic configuration. Okay.

Say likewise, Mg plus 2. Exact inert gas electronic configuration it will show. Right. So, Na plus, Mg plus 2, Al plus 3, Al plus 3. All of them come under cation with inert electronic configuration. Okay.

And the other type of cation you see. Cation with non-inert. electronic configuration, okay. Say lead, if you take up lead ion, you know, it will not show, you know, inert gas electronic configuration, right.

So, such cations are called non-inert electronic configuration showing cations, right. And coming to third category which is very important, cations with pseudo inert pseudo inert electronic configuration example for this is Zn plus 2 Cu plus Ag plus okay so all of them will come cadmium okay so cadmium plus 2 will come you know all these d block elements specially zinc plus 2 Cu plus 2 Ag plus 2 Cd plus 2 all of them will come. So let me tell you what is this pseudo inert electronic configuration. So observe the ion Zn plus 2. Okay, first let me write only zinc. What is its electronic configuration?

Its electronic configuration is argon till 80. See its atomic number is 30 till 18. You know, it's the electronic configuration of argon and later you will have 3s2, 3p6, 4s2. Okay, 3d10. Okay, Zn plus 2 electronic configuration is how much?

Argon 3s2 3p6 these electrons last shell means fourth shell. So, in this shell 2 electrons if it loses it becomes Zn plus 2. So, its electronic configuration is 3d10. So, this is not same as any noble gas electronic configuration this electronic configuration is not similar as any noble gas electronic configuration but this is stable only this is stable itself you see all orbitals are completely filled s orbital with two electron p orbital with six three orbital with ten that means our third shell is completely filled with 18 electron okay so our third shell is completely filled with 18 electron it is completely stable but electronic configuration is not similar electric configuration is stable right but not similar to but not similar to Any noble gas, any inert gas, right? So, such a configuration, electronic configuration is called pseudo inert electronic configuration. Okay.

So, usually try to remember Zn plus 2, copper plus, Cu plus, Ag plus, Cd plus 2, all these cations if they are there in a compound, they will show more polarizing. polarization okay they will have more polarizing power so that's why those compounds will have more covalent character okay so these three points are very very important to understand okay say for example question can be asked this way now let us work it out with few questions so that you will get a clarity what actually i'm talking about look at the first question you have cu cl and NaCl. Okay, so my question is which has more covalent character? Which has more covalent character?

Okay, so this is the question. So how do you decide? Copper chloride Na plus.

Here copper's charge is plus 1, Na's charge is also plus 1. Okay. So based on the charge you can't decide. And cation should be small, anion should be weak right. So normally bigger cation say compared to copper sodium comes in the first group. So you know this sodium is comparatively big cation.

Actually speaking this is cation. cation which is big whereas this cation This cation is actually small. Okay. So this is the small cation and this is the big cation. What did the point says?

Cation should be small, anion should be big. So anion is common in both the compounds. Whereas cation, copper is small, sodium is big. So we can say copper chloride.

Copper chloride is more covalent. Isn't it? Because compared to sodium, copper is smaller cation.

Sodium is big. We know first group elements are bigger, right? And that is one point you can concentrate. Then the other point, looking at this copper, what is copper?

Copper is cation with pseudo inert electronic configuration. What is our answer? Third point says cations with pseudo inert configuration have high polarizing power. High polarizing power, high polarization. High polarization, more covalent character.

Isn't it? So based on this point also whenever you find these cations definitely they have more covalent character because all these cations will come under the cations with pseudo electronic configuration. So one is size is small the other reason is what this particular copper has pseudo, pseudo inert.

electronic configuration. So that is why you know this copper chloride has more covalent character. Clear? So this is how you can decide like among a given compounds which one is more covalent and which one is less covalent. So this is one important type of question for your competitive examinations.

So you have to be very very careful. And coming to the next question, So second question for this you are giving answer in a comment section. So please try this. You have KCL and you also have AGCL. So tell me which one has more covalent character.

My question is which one has more. Covalent character. Okay. So just based on the concept decide your answer. Clear?

Fine. And another question. Question number 3 also try to give answer. KCl, NaCl.

Okay. So here you are telling me which one is more ionic. Which one is more ionic.

Okay. So based on the Farzen's rule, you can work on with these questions. So two questions I asked you.

One is this KCl and AgCl. Among them, which one is more? Covalent which has more covalent character. Second question is KCl and NaCl and tell me which is more ionic. Don't forget to post your answer in the comment section.

Let me know who is answering first. Okay. So that is all about covalent character in ionic compound.

I mean entire things about polarization. Okay. And now we will go for other aspect.

So now every covalent compound has ionic character, isn't it? So how do we decide that ionic character? You know, that is with the help of a concept called dipole moment. So let us understand everything about dipole moment. See guys, this dipole moment is also one of the very, very important concept that you have to concentrate.

So as I have already explained you, dipole moment will help you to... decide ionic character in covalent bond. So let us understand what actually we mean by this dipole moment and how do we find this dipole moment. Okay, so let me take a covalent compound HCl. Okay, so it has a covalent bond between hydrogen and chlorine.

This covalent bond which means the presence of two electrons exactly in between hydrogen and Cl. But there is electronegativity difference between hydrogen and Cl. Right? So there is... There is...

High, high electronegativity difference, electronegativity difference between hydrogen and Cl. So Cl is more electronegative here. So this has a ability of pulling this bond towards itself, right?

So what happens? This bonding. slightly moved more towards Cl.

This moving of bond towards Cl creates, so this particular concept creates dipole, creates dipole in a molecule. So what do you mean by dipole? Dipole in the sense charge creation. See when a bond is slightly moved more towards Cl, Cl will have a slightly negative charge.

Hydrogen will gain a slightly positive charge. That means see in a bond there was hydrogen's electrons. Now it is not completely belong to hydrogen. It is not even shared. You know that shared electron was moved more towards Cl.

It's like hydrogen have lost that electron. Not completely lost, slightly it is losing its electron, right? So, that's why a slight positive charge on hydrogen, okay?

So, this delta meaning in chemistry is slightly positive. Whenever we write delta positive, it means hydrogen is not completely positive. It has not completely lost electron. It is in a, you know... deficiency of electron it is having a deficiency of electron slight deficiency of electron so that is indicated with this sign slightly positive and this we call it as slightly negative okay so it has not completely took the electron of hydrogen just the bond is slightly moved towards Cl because this is more electronegative so bond will always move towards the atom which is more electronegative.

So why the bond has moved towards Cl? Because electronegativity of Cl is more than electronegativity of hydrogen. So that is the reason bond has moved towards here. So this this charge creation, slight charge creation in a molecule is called dipole.

That's why we say ionic. So this is what ionic character, right? So it's like a positive part is there, negative part is there in a compound, right?

Slightly positive, slightly negative. This is what we say ionic character generation in a covalent bond. That's what we mean by dipole. Dipole means what? Observing this slight charge generation, charges in a molecule is called dipole.

Okay. So you will observe dipole only when there is a high electronegativity difference between the two atoms. Okay. So this is how ionic character is observed even in a covalent bond. And now the strength of dipole, the strength of dipole.

is measured is measured by a concept called dipole moment okay so what is dipole moment dipole moment is used to measure the strength how extent the charges have been developed in the molecule you know if the charge on two two atoms is more then we say more ionic character is there in a covalent bond right so the the strength of this charge formation strength of dipole in other words is always measured by dipole moment which has a symbol nu okay so if i have to give the definition of dipole moment it is nothing but you know the product of it is the product of charge you charge and distance between the two atoms. So that means say this is what the formula we write nu is equal to charge Q into D. So what is Q here?

Q is nothing but charge of ion I mean charge of atoms and d is distance between the atoms. So distance between the atoms is nothing but what? Bond length right? That's what we can also call it as bond length.

Bond length is the distance between the two atoms you know this distance we will call it as bond length. So charge into bond length or distance if you do you will get the value for nu that is dipole moment. Looking at the value, you can say whether a compound has more ionic character or less ionic character.

More the dipole moment, more ionic character is there in a covalent compound. So, how do you decide? More. If you have more nu, then more is ionic character.

right so this is what you need to understand and few more things let's let's come to the unit of mu here so you should have an awareness about units of dipole moment that is new in si system that is in mks system the unit is coulomb meter okay c for coulomb charge You know, charge unit is coulomb and distance, it is like bond length is nothing but distance unit is meter, right? So, coulomb meter is the unit. In CGS system, the unit is ESU into meter, ESU, electrostatic force is called as ESU, ESU into meters, okay?

So, and dipole moment has another unit, another unit. Okay, which we famously call it as Dubai. Debye which is represented as D.

Okay. So, here you need to understand 1 Debye is equal to 0.33 into 10 power minus 24 coulomb meter. Coulomb meter.

It is not centimeter. It is coulomb meter. Okay. Or 1 Debye is equal to 10 power minus 18 EFU. into centimeter.

Okay. So, one device value is this much in coulomb meter units and one device is this much in ESU centimeter unit. Sorry, here it should come centimeter, right, in CGS system. So, these are the units of, you know, dipole. moment okay so the most important unit is debi debi is just a unit okay so one debi is this much coulometer and one debi is this much esu centimeter so this this is what you need to understand and now you know we can actually calculate the percentage ionic character that is there in covalent compound so take down that formula percentage ionic character if you want to find out you percentage ionic character in any covalent compound the formula is observed observed dipole moment divided by calculated dipole moment into 100 okay so this formula is very very important guys so percentage to how much percent ionic character is there in a particular compound that if you want to calculate The formula is this observed dipole moment divided by observed dipole moment divided by calculated dipole moment into 100. So now we will see one problem where we can apply this formula so that you will get an idea how actually we calculate dipole moment.

So what is the major formula of dipole moment? It is the charge into bond length that is the distance between the two atoms. So these are the various units and this is how we can calculate percentage ionic character. Let us see one problem here. See this problem guys dipole moment of HCl is 1.03 d that means it is a observed dipole moment they have given 1.03 d.

Bond length of HCl they have given that is D they have given 1.27 angstrom. Calculate percentage ionic character. What is the formula?

Here we have observed U, observed dipole moment divided by calculated dipole moment into 100. Observed dipole moment they gave. We have to calculate calculated dipole moment right. So how do you calculate dipole moment? It is charge into dipole distance isn't it so what is the charge here in esu centimeter let us calculate mu in esu centimeter units i'm calculating so charge value in esu centimeter is how much 4.8 into 10 power minus 10 okay so uh charge we know charge of an electron is how much one unit charge one unit Charge value is how much?

1.6 into 10 power minus 19 coulomb. It is in coulomb. But in electrostatic units, its value is 4.8 into 10 power minus 10 ESU we say. Okay. So, in ESU, charge value is this much.

In coulombs, charge value is this much. So, I am calculating, you know, the new value in ESU centimeter. So, I took charge value in this units 4.8 into 10 power minus 10 into distance.

Distance I need to take it in centimeter. So, we all know 1 angstrom is equal to 10 power minus 10 meter which is equal to 10 power minus 8 centimeter right. So, how much 1.27 into 10 power minus 8 centimeter. So, what is the new value you will get here?

6.10 into 10 power minus 18. 10 power minus 10 into 10 power minus 8 is 10 power minus 18 ESU centimeter. And convert this into the unit. It is 6.10 into 10 power minus 18 divided by 10 power. See, if you want to convert this into a unit, you will have to convert this into a unit. Oh, one debate in...

You know CGS from CGS units to 1 to pi it is 1 to pi is equal to 10 power minus 18 ESU centimeter right. So I will divide by 10 power minus 18 this gets cancelled. So new value is 6.10 the pi. Okay what is this dipole moment? This is actually our calculated dipole moment.

So now you have observed dipole moment that is given in a question. This is our calculated dipole moment. So use the formula and find out. So post your answer in comment section. Okay.

So calculate post the percentage ionic character that is there in HCl bond. Right. So this is how we can calculate dipole moment.

See guys, using dipole moment, we can decide the shape of these covalent molecules or from knowing the structure of covalent molecule, we can say whether dipole moment is there or not. Okay, so that's what we will try to learn now. You know, identifying dipole moment from structure.

So, what I am dealing is identifying the covalent molecules. Dipole moment from structure of molecules. So this is also very very important thing one must understand. First thing you need to learn is your dipole moment is vector quantity.

So we know the properties of vectors, right? So vector quantity, it will be mentioned with the help of arrow mark. Dipole moment is mentioned with the help of, you know, dipole. Especially, I am not the dipole moment.

Dipole. in a molecule can be represented with the help of arrow mark. Okay. So you have to show arrow mark from positive atom to negative atom. Okay.

For example, you see carbon dioxide. Carbon dioxide has a linear structure. How do you know that carbon dioxide has a linear structure?

You will understand this in VSEPR theory that you will study next. Okay. So just as of now, you will know that carbon dioxide has a linear structure.

Okay. So you will know that carbon This is the structure of your carbon dioxide. And I want to decide whether carbon dioxide shows dipole moment or not. okay so if dipole moment is there then we say this particular compound has you know ionic character if dipole moment is not there then we say this will not have ionic character okay so how do you decide you see this is a positive part this is a negative part so how will you show the dipole it's a vector quantity say dipole will always move from positive to negative side so this is a vector And this here also dipole you will observe. Oxygen is electronegative.

Carbon is electropositive. So this is the dipole you will show. And vector quantity in opposite direction will get cancelled right.

So what is the dipole moment here? Dipole moment is 0. Okay. So I say this particular molecule is not having any ionic character.

Okay. So this is how from structure you can decide whether dipole moment is there or not. okay fine and you know another molecule let me take BF3 so if I have to write the structure of BF3 it is planar it is planar And how will you show the dipoles here? This is positive, this is electronegative. So here the dipole is always from positive side to negative side.

That's how you have to show the dipole. Okay, from understanding dipoles, dipole is a vector quantity. By understanding this dipole or these vectors, you can decide whether dipole moment is shown by a compound or not.

And this bond, how will you, for this bond, how will you show the dipole? Positive, negative. So, dipole you have to show this way. For this bond, how will you show the dipole? Positive, negative.

So, dipole is this way. And it is planar, okay? So, for planar and this is how the dipoles are, okay?

So, all in different directions and the molecule is highly planar. So, here also dipole moment will be zero. Remember, for any planar molecule, the dipole moment will be 0. Okay, fine. Now coming to very very important example, I will compare the dipole moment of NH3 and NF3. So if I ask you which has got more dipole moment among these two, which has got more dipole moment, then you can decide based on their structures.

Okay, so what is the structure of NH3? Structure of NH3 is pyramidal, right? H H, H and there is a lone pair.

This is and how do you decide that this is a structure and this is how we will write? It is based on the Vesper theory. Hold on. About Vesper theory we will discuss in our next class. Okay.

So this is NH3 structure. Okay. And NF3, and a lone pair. Okay.

So how will you show a dipole for this bond? Nitrogen, more negative, electro negative, hydrogen, electro positive. Positive to negative you have to show the arrow mark. I mean vector. Okay.

And how will you show the dipole? For every bond you have to show the dipole. From the direction you are deciding whether it will show dipole moment or not. Okay.

So NH bond. How will you show the dipole? Like this. NH bond, dipole like this. And nitrogen, and lone pair between nitrogen and lone pair lone pair is more negative so dipole is like this see all arrows are moving in a same direction say the resultant vector is very much strong right so you must know some basic properties of vectors here okay so when all these vectors are moving and joining at a single point the resultant vector is very strong so here Dipole moment is high.

Dipole moment is very much high. Okay. So very high.

Very high. Because the resultant vector is very very strong. Right. Okay.

And coming to NF3. So how will you show the dipoles for a bond? Compared to nitrogen, fluorine is more electronegative.

So the dipole is like this. And for this bond, dipole is like this. For this bond, dipole you will show like this. And here between nitrogen and lone pair. Lone pair is more negative.

So, dipole you will show up. And here you see one arrow direction will get cancelled with another arrows direction, right? So, if you take this above arrow and any one below arrow, they will get cancelled, right? So, the resultant dipole is due to only two arrows. The resultant dipole is due to only any two bottom arrows, okay?

So that's why here you will observe dipole moment but the dipole is less. Dipole is less. See the moment you see here you would think that NF3 has got greatest dipole moment because you know electronegative elements are 3 right. Fluorines are 3 but no NH3 has got more dipole moment that has decided by structure. Okay so to some extent.

extent these structures will tell you whether a molecule has greater dipole moment or lesser dipole moment okay so looking at the structure you can able to decide which has got more and which has got less dipole moment so let me meet you all in the next video with more examples of dipole moment and let me discuss all bond parameters thank you so much take care and keep revising

Transcript for:Understanding Chemical Bonding Concepts

Transcript for:
Understanding Chemical Bonding Concepts