 Hello, guys. Good evening, everyone. How are you? Okay, guys. So wherever we in the last class, could you tell me just a second? We'll start in a few minutes. Okay, so I think we had discussed Heisenberg uncertainty principle, correct? Yeah. And questions also we have discussed on that. Okay, so Heisenberg principle suggests that we cannot find out the exact position and momentum of an electron. Right? And this was the big blow for Bohr's atomic model, because unlike Heisenberg, he was suggesting that we had the exact position of an electron. It resides in orbit, which has a fixed distance from the nucleus. And in that orbit, it has a fixed kinetic energy, potential energy and its velocity, correct? So according to Bohr's, we know the exact position and velocity of electrons, but Heisenberg said the opposite of it, right? The statement given by Heisenberg, it is a contradictory statement to the statement of Bohr's model. Okay, that's why we discarded Bohr's model also later on. Okay, it was not completely wrong. But yes, it was not 100% correct also. A few things was not correct in Bohr's model. That's why we discarded Bohr's model later on. Right? So after this Heisenberg mechanical model based on the quantum mechanics developed by the scientist, mainly Schrodinger. Okay, and based on that, we talk about the presence of electron, where the electron presents, what is the exact thing within an atom in which the electron is present, we get all those ideas, right? That is based on quantum mechanics, right? That is wave mechanical model. Okay, so this, you know, obviously the quantum mechanics, we won't be able to understand it properly at this level. So we'll just take few reference of it. Okay, we won't go into depth of it. We'll take few reference of it to understand the Schrodinger equation. Okay, so one statement first you write down and then we'll move on to it. Write down the statement. When Heisenberg uncertainty principle, I'll also write down it. The statement is when Heisenberg based on the data given or like an easily find out. Yes, with practice, you will have the idea of it at which formula we should use. But based on the data given, you can understand. So write down this particular statement here. When Heisenberg uncertainty principle, when Heisenberg uncertainty principle came into existence or came into picture, picture, the concept of the concept of electron revolving around the nucleus, around the nucleus, in different orbit, in different orbit where the position and velocity, velocity are exactly known was replaced by was replaced by was replaced by the probability was replaced by the probability of finding an electron in a particular, particular space or volume, right? So after Heisenberg, we said what that, you know, the concept that we get is, this is an orbit, suppose we have, and this is a volume, right? So initially, Bohr suggested that electron revolves in a fixed path called orbit, circular path called orbit. This is a nucleus. So this is orbit, right? Since Heisenberg suggests that the exact position and momentum we cannot find out. So fine, we said what, okay, we cannot pinpoint the location of electron, but we can say, okay, the electron present in this region. In this region, definitely the electron is present, right? So the certainty here, it, you know, it converts into probability. After this Heisenberg, we started talking about the probability of finding an electron. We don't talk about certainty now, but we started talking about the probability of finding an electron, right? So this is the three dimensional space. And in this space, we can say the probability of finding an electron is maximum, correct? So this was the biggest, you know, achievement of this particular scale. We are not talking about a pinpoint location of an electron, but we are talking about a volume in which the probability of finding an electron is maximum, okay? What is this? This is three dimensional space or a volume, 3D space. After this concept only, the entire thing, we got to know about a new concept and this concept we call it as orbital, right? So after this only, like I told you in the beginning, there's nothing called orbit within an atom. It's the thing is orbital, not orbit. The concept of orbit was vanished after this, and we started talking about orbital, the ITL, orbital, right? So write down the statement here, just one line we have. It is a three dimensional space. Orbital write down, it is a three dimensional space. Orbital write down, it is a three dimensional space where the probability of finding an electron is maximum. Right, this is what orbital. So after this, we won't talk about orbit. Orbit is nothing like it won't exist. The correct thing is orbital, right? So this thing, we came to know when, when we got to know the wave characteristics of electron from de Broglie wavelength, right? That all microscopic particles, when in motion, when in motion contains wave characteristics, and when we study these wave characteristics, we'll get to know about all these things, correct? So this is, after this only, a new model has been developed given by the scientist, mainly Schrodinger, okay, but the research and the study was done by Heisenberg and Sainte, and the scientist, Schrodinger and Sainte and Schrodinger both, right? And this we call it as quantum mechanical model of a, write down, quantum mechanical model, okay? So what is quantum mechanical model? Write down, it is based on the quantum mechanics. It is based on quantum mechanics. See, they are basically two things. One is classical mechanics. Other one is quantum mechanics. Classical mechanics, where we have the Newton's laws of motion, and all these things are valid, right? On mic, on macroscopic objects, like any object, we apply Newton's laws of motion. But when it comes to microscopic objects like electron, which consists, which contains both particle as well as wave characteristics, okay? So the particles which has dual nature, for those kind of particles, the classical mechanics fails. It is not valid, right? Don't give you correct reason, classical mechanics. Newton's laws of motion, we don't apply into that, right? Basically Newton's laws of motion, that is, classical mechanics is applied from macroscopic particles, not for micro, okay? For macroscopic particles. So for microscopic particles, we have quantum mechanics. We used to understand the behavior properties with the help of quantum mechanics, right? The quantum mechanics, it is based on quantum mechanics. Next slide down. Quantum mechanics is a theoretical science. Quantum mechanics is the theoretical science that deals with the study of the motion of microscopic objects. The theoretical science that deals with the study of the motions of microscopic particles, which has both, or write down, which has dual characteristics, which deals with the study of the motion of the microscopic objects, which has both characteristics. Both characteristics means wave and particle nature. Okay, next time you write down, it is developed by Heisenberg and Strodinger. It is developed by Heisenberg and Strodinger. Heisenberg and Strodinger. Now you see what happens here. Strodinger actually, he defines a new function here. To understand this behavior, he defines a new function that is psi represented by this line. This kind of threshold if you have sin log Shiva, okay? Similar kind of, no, term we have here, right? This we call it as this kind of this, okay? This is psi. This is psi, the term we call it as psi, okay? So Strodinger has given this term and this term is called the wave function, wave function or amplitude function, amplitude function, wave function or amplitude function, okay? This, you know, you can compare this with the amplitude of any wave, any light wave, like light wave has some amplitude, any wave has some amplitude. So this is the amplitude of electron wave, you can say. It is the term we define, we define for the waves associated with electron, correct? And hence we call it as the amplitude of, actually it is the amplitude of electron wave, electron wave, okay? So light wave, for example, you see, for example, if you have light wave, light wave has amplitude A, suppose, has amplitude A. Suppose I'm assuming this, right? Then what we say, the intensity of light wave I is directly proportional to A square, the square of the amplitude, right? Similarly, if you have an electron wave, an electron wave with amplitude, with amplitude psi, okay? So intensity of electron wave is also directly proportional to psi square, okay? I'm discussing these things here, but you won't get question on this, okay? I'm just discussing for you to have an idea of it, nothing much, you know, required here. Intensity is psi square. Since this represents the amplitude function or wave function of an electron and intensity is directly proportional to psi square, this means what? Psi square is what? Psi square represents the intensity of electrons. Psi square represents intensity of electron. If you have more value of psi square, more will be the intensity of electron and more will be the probability to get an electron, right? That's why psi square, we also call it as probability per unit volume, probability per unit volume. This also, we call it as probability density function, probability density function. So this is what you should understand. What is psi? Psi is the wave function or amplitude function, but psi square is the probability density function. Density means per unit volume calculation we are doing. Charge density means charge per unit volume. Similarly, probability density means probability per unit volume, correct? So these are the two terms given by them, okay? Now, with the help of this wave function, one more thing, this wave function actually, it consists of all informations of electron, okay? It consists of, consists of all information for an electron, for an electron. Suppose if you want to get some information about electron, you should take wave function of that particular electron and you should study the wave function. That is it. It gives you all the properties of electron, like its energy and other things, right? Okay, one point is this. Another point, it is probability per unit volume. So suppose we have psi square is probability per unit volume. Suppose we have a volume, every small volume we are considering, right? This is the volume and the volume is three dimensional thing, right? So if very small volume we assume, that is dx into dy into dz. This is a very small volume we have. We are considering this, right? Very small volume. So psi square is equals to, we have already seen, it is probability per unit volume, okay? So probability if you find out from this equation, probability is equals to psi square into volume. And that would be psi square into dx, dy and dz. This is the probability. So if you integrate this three times, because we have three terms, dx, dy and dz, psi square dx, dy, dz, this gives you the probability of an electron in this particular volume. In this particular volume, okay? So maximum probability is one. So probability of getting an electron is triple integration of this. Psi square dx, dy, dz is equals to one. The maximum probability is this. Now, for different, different volume, you don't have to solve this. Triple integration is not there in your textbook, right? So for different, different volume, we have different value of psi also. Is it, Shatish? Okay, we'll quickly then, I forgot, you did not tell me. Anyways, can you tell me what is the last portion I discussed? Okay, we did Honsun. Okay, fine. So that's why I was thinking that you are not asking any doubt. Okay, anyways, so guys, we have done it already, no? Anyways, okay, okay, fine, I got it, I got it. It means we have done all those things, quantum number, other things we have done, right? That's fine, no problem, just you will, okay, fine, you had a revision of it. Fine, so actually, okay, electronic configuration we have done, Honsun we have done. Okay, nodal surface we need to do. Okay, one last thing you'll see, see this equation actually, it has two components. I'll tell you what it is. This equation has two components, I'm just leaving all these things now. Psi actually has two components when you solve this. I'm doing this, you know, for you is to, because one question they ask into this, a pattern is there. I'll show you what that pattern is. Okay, just a second. This orbital wave function, if you solve, it has two components. This one I haven't done, so you can copy this down. Psi has two components, that is, Psi will write R, that is a radial point of it. And this one is the angular part of it, theta and phi, theta and phi. So basically, if you consider an axis, only one question they ask on this, I'll show you what kind of question they ask. Suppose we have an electron present somewhere here, this is the point here. So it will have some distance from the nucleus, correct? So this is the distance we have, suppose. This is the radial distance, that is R, this part. We'll have some angle over here, theta. And when you place the perpendicular line from this, like this way, we'll have some angle with this axis, that is phi. Okay, this is not theta actually. Theta is this side, this side is theta. So this represents the angular position of this electron, theta and phi. And this is radial, the distance from this nucleus. So this part is radial, and this part here is angular, radial and angular, okay? This radial part of the wave function, so wave function has two parts, radial and angular. Wave function depends upon the two value, depends on the principal quantum number N and azimuthal quantum number L, N and L, right? It gives us an idea of size of the orbital. Size, we have an idea of size from this. Angular part is, it is the angular part of wave function, right? And it is represented by L, I'll write down here L, azimuthal quantum number. And it depends upon the two value on L and magnetic quantum number M, right? And it gives us an idea of shape of the orbital, idea of shape, okay? So that's why from Stradinger wave equation, we got to know about three different quantum numbers N, L and M, right? Not the spin quantum number. Now what question they ask? This sometimes gives you this relation. They'll write down the wave function this way. That is, suppose I write down 420 here, right? Like this, they'll write down, and they'll ask you, which orbital is this? Like this, they ask the question, okay? This number that we have written here, 420, this actually in the order of this N, L and M. So if you see this number, it means, if you compare that to N value is 4, right? L value is 2 and M value is 0. Could you tell me the orbital with this three quantum number? Which orbital is this? Tell me which orbital is this? L value is 2. So it is D. It is not P, she says, right? So it is 4DZ square because M is 0. So this is what you can understand from this particular information. I'll change, oh, just a second. Next, yes. The next, we have to understand the last concept here of this chapter. Right? That is nodal surface. Very simple one, two, three things you have to keep in mind, nothing much. Write down, these are the surface. These are the surface where, surface where the probability of finding an electron. These are the surface where the probability of finding an electron is 0, or finding an electron is 0, right? So we have nodal surface. Nodal surface, we have two types, okay? One is a spherical node or radial node. Two types, the first one, write down. A spherical node, we also call it as radial node. A spherical node means we have a, yes, nodal surface. It is a surface where the probability of finding an electron is 0. It is a surface where the probability of finding an electron is 0, correct? Two types, we have a spherical node or radial node. Both are the same thing. A spherical node means what will happen spherical surface, where the probability of finding an electron is 0, right? Just you need to memorize the formula we use to find out the spherical node and the formula is N minus L minus 1. It gives you the number of spherical nodes, okay? Another type we have that is non-spherical node, non-spherical node. We also call it as angular node, angular node. The formula of this is L. It's non-spherical. We don't represent this on the graph, okay? There's this formula you should know. And few things I'll tell you what you have to keep in mind quickly here. So if I ask you what is the total number of nodes, that would be the sum of the two, N minus 1. Now, there's a graphical representation of these nodes, easy one that you have to understand, okay? I'll show you the graph here. Just a second. All of you copy down this. Could you tell me how many nodes we have in 1S orbital? Number of nodes in what S orbital? Tell me. Number of nodes in 1S, number of nodes in 2S, total number of nodes, if I ask you, the spherical node here, just you need to use the formula. 1 minus L value is 0. This is 0. Angular node is also 0 because it is S sub-shell. Angular node is 0. So there is no nodal surface for 1S orbital, right? If you talk about 2S, then the number of spherical node is 1. Spherical node is 2 minus 0 minus 1, that is 1. And the number of angular node is 0 again because S sub-shell. Angular node would be always 0 for S sub-shell. Now, based on this number of nodes that we have, we can discuss for the graph here. Just a second. I'll show you the graph. Just a second, Pradyum. See node, Pradyum node is a surface where the probability of finding an electron is 0. Right? It is a surface where the probability of finding an electron is 0. That is what it is. Okay. So you see this graph. I'll explain this graph. Two, three points you have to understand here. First of all, if they ask you the number of nodes, you can find out easily, right? That with this formula that these are the nodes present in this. Now, based on this, we can draw the graph. You see, for 1S orbital, we have the graph of psi and r, psi square and r. And it is psi square, 4 pi r square d square. You see this term here. This term is present over here. So psi square, if you remember, it is the probability per unit volume. And if you multiply this with 4 pi r square, which is a surface area, into dr, this term becomes the volume actually. So this integration of this, it represents the probability. So this axis is probability. And this is the distance from the nucleus. Did you understand the three, you know, the three graphs where we have the axis. This is psi and r, psi square and r and probability and distance from the nucleus. r is the distance from the nucleus. So these two graphs, we do not have any control because we don't know the relation of psi and r. But this will be a curve here. It won't be a straight line like this. So psi r graph goes like this. Psi square r graph, more steeper curve, goes like this. And psi square r, that is probability versus r graph, it goes up, will have a maximum probability, right? And then comes down. But remember, this graph won't touch the x axis. Otherwise, the probability becomes zero, which is not the case of oneness orbit. Did you understand the first three graph? Just a second, guys. Just a second. I think I have a better picture of it. Let me just cross check. Oh, I think it's got deleted. See this graph only. See another class I had drawn this. So first three graph, did you understand? So you was there in the last class of quantum number. N is the principal quantum number and L is the azimuthal quantum number. Yes. So before coming for the class, you should must revise once quickly, right? A brief revision is must required. Okay. So did you understand the first three graph? Obviously, you see psi and r relation, we do not have. So it is a curve. It goes like this, right? If there is no node, then this graph won't cross the x axis. It will be above x axis. Third graph, did you understand? Third graph is more important. The probability of a graph is more important. Did you understand the third graph? And did you get it? Now, if you see two s orbital here, but two s orbital, we know we have one node here. Means there will be one spherical surface where the probability of finding an electron is zero or there is no electron present here. Yes. Psi square is probability density. That is nothing but probability per unit volume. Okay. So since we have one node here, that's why this graph you see it comes down, crosses the x axis and then goes up. Just convention wise, we'll write this says above this is positive and this is negative. And you see this is psi wave function. And wave function I told you already, it can be positive, can be negative both. Right. That's why we have positive negative both. And this point where it touches the x axis, then psi is zero here. Psi is zero means psi square is zero. Psi square is zero means probability is zero. And when probability is zero, that point here, it becomes the node. Did you get it? Psi square, you have to just draw the mirror image of this negative part. This negative part becomes positive. Just above this will draw. Remember both the graph here and here further it won't touch the x axis. If it touches, it means that point also we have a node which is not possible because we have only one node here. Right. Then probability graph, if you see it goes like this, probability graph always starts from the origin because we know electron cannot present in the nucleus. Right. Always in the nucleus here, the probability is zero. Always this graph you see it starts from the origin goes up and then comes down. Now, if you have this kind of graph because like I said, probability graph is more important. If you have this kind of graph, the peak that you have, the mountain structure that you see here. Right. If you have two peak, right, then we'll have one node. That's what I have written here. Number of peak is one more than the number of node. Probability graph always starts with zero. Right. The point at which it touches the axis here, there, the probability becomes zero and that becomes the nodal surface. Did you understand this? Yes, all of you got it. No doubt. Please respond. Okay. So you should know the graphical representation, what things we can conclude from the graph. That is one type of question they ask. One type. They'll ask you that the number of nodes present. So for that, you just use the formula. You'll find out the number of node. Okay. Another thing that you should know that what are the nodal planes we have for different, different orbitals. Right. It's very simple. You see, if the for to be orbital, we write here to be orbital number of spherical node is n minus L minus one. That is two minus two minus one minus one. That is zero. There's no spherical node and the number of number of angular node, non-spherical is one here. Right. If the orbital is px for px orbital, we have one angular node. That nodal plane for this is YZ plane perpendicular one. Right. The perpendicular plane is YZ plane. And this is the nodal plane for px orbital. Right. If you have p y orbital, the nodal plane is XZ the perpendicular one is the nodal plane. If you have pz orbital, then the nodal plane is X, Y plane, Y plane. And this is the answer here. You should know what are the nodal planes we have. Similarly, if you think you have to memorize. Okay. 3d orbital, you're going to copy down this one. I'll go to the next page then. Okay. Now, if you talk about for 3d orbital, could you tell me how many nodal surface we have for 3d orbital? Spherical node 2. That's right. Spherical node is 3 minus 2 minus 1. That is 0. And angular node is 2. Okay. So if it is, you see here, if it is DXY orbital, it is an XY plane. So YZ and ZX, YZ and ZX are nodal planes for DXY orbital. If you take DYZ, then the nodal plane is XY and Y, XY and ZX, XY and ZX. If you take DXZ, the nodal plane is XY and ZY. So we have two nodal planes here. One exception we have into this one. Right? Right down the node. I'll just copy down this. DZ square has no nodal planes. DZ square has no nodal plane. But it has, but it has nodal surface as cones, conical shape we have there. Right? The nodal surface as cones, C-O-N-E-S. Okay. So this one is an exception. You must remember this. So this is it for nodal surface. Okay. They will sometimes ask you that what is the nodal plane for this one or nodal surface for this one. You should know like is the perpendicular one is the nodal plane or nodal surface. Now, this is the second type of question they asked. Third and the last type here we have. So fourth and the last type we have. One is relatively the number of nodes. Other one is the graph types. Third one is this. What are the, what are nodal planes we have. And the fourth one is this type of question I will show you here. The question is the wave function for 3S electron is given. So wave function is psi. Psi for 3X is given. 3S not X. Psi for 3S orbital is given. Is 1 by 81 root 3 pi into 1 by a naught. 3 by 2. It's 3 by 2 open bracket. 27 minus 18. R by a naught. Plus 2. R by a naught. Square. Close bracket. E to the power minus R. 3 a naught. A naught is the. Orbit the first radius of the first orbit. This is the psi value it is given relation of psi and R. It says the wave function of 3S electron is given by this. And it has a node at. R is equals to R naught. Find the relation between R naught and A naught. Try this one. What's it is. This equation you are saying. Yes. This equation you will get once you solve the. Srodinger wave equation. That Hamiltonian things and all. But that is not there in the slivers. Right. So we don't have to do with this equation. Anything. Just need you. You just have to use one condition and that is. That's right. And. That is what you need to do. Where is E we have. We do not have here. R by a. E is the electron. No. That exponential. E. E to the power. Answer. I'm not sure with I have to do this. All of you solve this. Anyone. I got one response for the. Others. What is the answer you are getting. Okay. Fine. You can take the help of calculator if you want. Yes. It is a square. That's why it has two values. Okay. Fine. I'll do this. I don't know the answer. I'll just have to do this. Okay. See this. It has a node at R is equals to R naught. Node means what. If the probability will be zero. Of finding an electron. Psi square is zero. And that means. Psi is zero. So Psi for three s. At R is equals to R naught is zero. So we have to substitute this. Psi goes over here and solve this equation. So when you substitute, you'll get. R naught by a naught. Plus two times. R naught by a naught. This is a. R naught by a naught. A square is equals to zero. That is what you need to solve. So when you solve this quadratic R naught by a naught is equals to. 18 plus. Minus. Four into two into this. That is 216. So could you tell me the answer here? 18 plus minus this is three 24 minus two 16. So it is 100. 108 root over by this. Tell me this value. What is the root over of 108? Okay. So it is 10.4 plus minus this. So we have 28.4 by four. And. Seven point. Sorry. 10.4 18 minus 10.4. That is a 7.6. By. So that would be. Seven point. One. And. One point nine. R naught is equals to we get here. Point one a naught. And R naught is equals to. One point nine a naught. Now you see one thing if you observe here you'll understand this particular thing very easily. If I ask you the question. How many nodal plane. Three S orbital would have. Three S. How many nodal plane for three S. It is two. Right. A spherical and no angular node to a spherical note. Means we should have two surface from the nucleus. A spherical surface. Where the probability of finding an electron is zero. This is one surface. Another surface according to this point right. Zero. And that's why we have two value of R naught here. Did you get this. At this distance from the nucleus. And this distance from the nucleus. We'll have two spherical surface. Where the probability of finding an electron is zero. Yes. That is technically not possible because it is for three S. It is for three S. Right. Then we should have two nodes. Then the equation must be quadratic. Correct. Hence we must get two values here. A perfect quadratic you're talking about. No that won't be the case. You won't get it here. So for those orbitals where the spherical nodes are three. You will have a cubical equation here. Right. You will have a cubical equation. So one thing also you can observe. I they have mentioned this three S over here. Sometimes what happens they'll just give you the wave function for an orbital has this relation. They'll give you like this. Then what is the number of nodes we have here. The number of nodes would be the solution of it. Number of nodes would be the solution of it. Right. So in that case if you are getting perfect square. Then we'll have only one node there. However the square is the. You know the equation is a quadratic equation. But if three S is mentioned then you won't get perfect square there. If four S is mentioned you won't get perfect square there. Right. If they have mentioned two S. Then it is possible to have perfect square. What is X to the power q minus one. See equation. See. Equation. Yeah. Equation could be anything. It could be anything. You are giving the simplest one. The equation won't be that simple. Right. It could be anything. But we should have three different values for three spherical nodes. Yes. We can have imaginary plane also. All these are orbitals are also imaginary. It is not like there's a double kind of thing present within an atom. But if you're talking about imaginary in terms of complex number. Then that won't be the case here. You won't get that kind of equation. Okay. Understood this. Yeah. So that that kind of equation root over of minus minus one. You won't get that. Those kind of equation you won't get. So these are the three four types of question they ask in. You know, you can understand these three four things how to solve the question. And that is whenever you get this kind of equation. No. You have nothing to do, but you need to put size equals to zero. That is how we'll proceed. So this is it for this particular chapter. That is atomic structure. We have done everything in. So far. So far. So far. So far. So far. So far. So far. So far. So far. So far. So far. That is atomic structure. We have done everything in, So detailed. So we'll start with the next chapter. And that is periodic classification or periodic properties. See, in this particular chapter we are going to study about atomic city, I have used a term electronegativity remember that this one we have only spherical no angular nodes here that we cannot see from this one right since we have R value so we can only get the radial nodes spherical one no we can only get the radial one from this okay so next write down the chapter we are going to start with periodic properties so I was talking about electronegativity remember we have used the term electronegativity in organic so those kind of terms we are going to see in this chapter right so those kind of terms we are going to understand here in this chapter okay what is the term what is the application and other things correct so first of all we'll discuss about the periodic table right you must have the understanding of periodic table first okay and then we can talk about those terms that we have to discuss correct so periodic table when we got to know about different different elements then we try to arrange those elements in according to their you know properties or we can say electronic configuration or according to their atomic number atomic mass so in that way I will discuss or you know in that way we have we've got different different theories that atoms are arranged in this way like the frost has given one theory one we have new land octave rules we have one is dobernier triad, mendeleevs, fluid table and then modern fluid table right so few things are important here we'll discuss all these theory one by one so these things are actually similar to the atomic models that different different scientists they have given their own theory you know regarding the distribution of subatomic particles within an atom and those theory we call it as atomic models so here also we have different theories of arrangement of atoms means how do we how can we arrange an atom in a proper form in a proper way so that we have different different theories you get okay so the first theory that we get is it is given by the scientist called frost okay I'll just write down just a second so the different theory is given by the different different scientists and this will discuss under the development of periodic table periodic table okay all of you write down the first theory that is given here is we call it as proud's hypothesis obviously this was not correct wrong and hence we discarded discarded it later okay so what he suggests that all atoms in the world is made up of hydrogen only write down quickly these things are not important even the recent I know the slavers of thing they have changed this thing this is not given in your slaves but for Jay sometimes they ask questions on this the background of the history of all this that's why I'm doing this okay write down all of you according to this all elements are made up of hydrogen made up of hydrogen and the atomic weight of any element is given by atomic weight of any element is n where n is the where n is the number of hydrogen atom present in this number of hydrogen atom present so obviously this was wrong so we discarded it right so this was wrong the second theory was was dobernier tried to this one is important you'll get question on this also dobernier tried who d o b e r n i e r all of you write down write down he suggested that within a group of three elements he suggested that within a group of three elements of similar physical and chemical properties of similar physical and chemical properties similar physical and chemical properties atomic weight atomic weight atomic weight of the middle element atomic weight of the middle element is the mean of the other two example you see if you talk about lithium sodium and potassium okay the atomic weight of lithium is seven potassium is 39 and the average of these two is 23 and 23 is the atomic weight of sodium so it is a dobernier try okay if you talk about sulfur selenium and tellurium it is 32 sulfur is 32 sulfur is 32 and this one is 128 and the average of the two is 80 selenium is 80 these three forms are dobernier try okay chlorine bromine iodine it is 35.5 chlorine iodine is 127 and the average of the two you see if you get here 54 plus 8 162.5 divided by 2 the average we are getting 81.25 the average but the atomic mass of bromine is 80 so it is close actually not exact value but it is close and forms a dobernier try similarly we can find out for the other you know elements also so these kind of elements dobernier he suggested that the elements of physical chemical or similar physical and chemical properties forms this kind of try okay but this also not valid for all the elements so we have we discarded this particular thing also but in the test and question in the book also you see they'll ask you this question which of these groups shows dobernier try or follows dobernier try okay did you copy this third theory we have new land octave rules octave rule or octave law okay write down this according to this theory write down according to this theory if the elements are arranged if the elements are arranged in order to their in order to their increasing atomic rates if the elements are arranged in order to their increasing atomic rates every eighth element every eighth element will have the similar properties the eighth element will have the similar properties to the first one like the first and eighth note in music like the first and eighth note in music write it down I'll just discuss you discuss with you okay again I'm repeating this if you arrange in order to their increasing atomic rates every eighth element had will have the similar properties to the first one like the first and eighth note in music for example you see if we have lithium beryllium boron carbon nitrogen oxygen chlorine and then again sodium magnesium boron silicon phosphorus sulfur chlorine and potassium see it is one two three four five six seven eight right every eighth element will have the same properties like we have first and eighth note of music like sa re ga ma pa da ni sa right again you see ni sa first and eighth one have the same thing right same note we have sa and sa similarly the property of lithium and sodium is also very similar okay so this is what this is newland octave rule but this is also not found to be correct and hence we discarded this also this one and this one this is the rule right next one the fourth attempt was made and this we call it as lothal mere curve lothal mere curve I'll show you this curve you don't have to draw this okay just I'll explain few points here this is lothal mere curve here this curve is drawn between between atomic volume and atomic mass this is the first thing you should keep in mind atomic volume and atomic mass then what he observed here that all the electropositive elements right elements of first group lithium sodium potassium no rubidium cesium all electropositive elements alkali metals the first group occupy the peak of the curve it present over here you see this lithium sodium potassium rubidium cesium this red dot is alkali metals group one okay the lesser electropositive element which is the elements of group two right it occupy the descending position of the curve you see this beryllium comes over here it occupies the descending position beryllium then magnesium then calcium strontium beryllium right this is alkaline earth metal group two similarly non metals and metalloids are in the bottom of the curve we have like this you see metalloids cobalt copper zinc non metals fluorine domain here right we have sulphur here zirconium here iodine here all these are on the bottom of the curve so what he said actually that on the basis of this curve he what he concluded right on this point he proposed that the physical property of the elements the physical properties of the elements physical properties of the elements just a second yeah I'm repeating it on the base of this curve he proposed that the physical properties of the elements are periodic function of their atomic weight their atomic weight so from this particular thing we came to know about this fact that physical properties are the function of their atomic weight right atomic weight this becomes the basis of the next theory and that is the mentally periodic table okay write down this becomes the basis of mentally periodic table which is the next theory atomic weight you see this periodic function of their atomic weight this becomes the basis of mentally periodic now what is mentally periodic table the modern one that we are using it is just the modified version of mentally periodic table okay so write down the heading mentally periodic table okay write down this periodic table is based upon the fact this periodic table is based upon the fact that physical and chemical properties of an element based upon the fact that physical and chemical properties of an element physical chemical properties of elements are the periodic function of their atomic weight of their atomic weight so this table a mentally periodic table it is based upon the atomic weight not atomic number atomic weight right so basis is the atomic weight first thing is that and what he did actually he was the first scientist who arranged the elements in horizontal and vertical manner length means horizontal rows and vertical columns right and this horizontal rows are called periods and the vertical columns are called groups so according to mental if that time there were seven periods seven periods and periods means horizontal rows groups and eight groups that is vertical column vertical column next next point you write down each group up to seven each group up to seven is divided into two subgroups a and b each group up to seven is divided into two groups a and b so we have two subgroups so subgroup a is the normal element normal element up to seven it is right and subgroup d it is a transition element transition element okay next next point see why these points the facts are important because sometimes especially for mental if sometimes they'll ask you this question which statement is correct with respect to the mentally periodic table so these are the informations you should have that's why i'm dictating you this next write down that the eighth group was consist of nine elements the eighth eighth group was consist of nine elements next one the elements belongs to same group exhibit similar properties right elements belongs to the same groups has similar property and hence this was the biggest achievement that the study of elements becomes easier the properties of the elements because same group elements have similar properties that is what that that's what the biggest advantage here okay mentally if they will the disadvantage was what that write down the disadvantage is or drawback you can say is the position of hydrogen is uncertain the position of hydrogen is uncertain it has been placed in one a and seven a it has been placed in one a and seven a group seven a group because of the resemblance with both groups you there are many different different points we have in this i have just given you the the important one which you should keep in mind okay all those things you don't have to memorize clear now based on this only like i said mentally was the first one was the first scientist who arranged the atoms in elements in that horizontal and vertical fashion okay rows and column concepts he bring in right based on this only we have our modern theory table that we also call it as modified mentally periodic table or modern periodic table right so write down the heading the last one in this that is modern periodic table which is nothing but modified mentally periodic table right proposed by mostly it is proposed by mostly based on atomic number so this is the biggest difference in the the previous one was based on atomic mass and this one is based upon atomic number what he did actually he took a metal elements like metal atom right metal surface he took and on this metal surface he bombarded he bombarded high speed electrons high speed electrons on different different metal surface means with different different metal surface this experiment is done and what he observed that that when it strikes this metal surface it emits x-ray right from the surface of the metal it emits x-ray this is mostly experiment it emits x-rays and the frequency of this x-ray that is new is found to be directly proportional to the atomic number it is actually root over of it root over of frequency directly proportional to the atomic number right and when you write down the relation here this new it becomes root over of new is equals to a into z minus b where this z is the atomic number a and b are constant just a second and write it down a and b are constant here are constant that is the atomic number so what happened here it took a metal surface different different metal surface and it strikes high speed electron on this metal surface and he observes that that x-rays comes out in this experiment right and the frequency of this x-rays the root over of it is directly proportional to the atomic number of the metal that we are taking in we have a graph for this actually okay the graph when he plotted of different different frequency with atomic number and root new right into 10 to the power minus 10 you'll get a graph like this straight line passes through origin and hence the relation is okay this is the modern period table that is modified period table right and this we also call it as the long form of periodic table right long form modern period table right on few characteristics of this few properties here this modern period table or long form periodic table based on mostly is experiment the experiment i'll show you right that experiment that way that metal surface strikes with the high beam high you know speed electrons based on this experiment the long form period table it gives it contains seven periods 18 groups vertical columns 18 groups the elements belongs to the same group elements belongs to the same group has the same number of electrons belongs to the same group has the same number of electrons in the valence shell so these are the properties we have for long form or modern period table few facts in this you write down write down bromine is the only non-metal which exists in liquid form bromine is the only non-metal which exists in liquid form iodine is solid iodine is solid bromine is the only non-metal exist in liquid form there are 11 gaseous elements there are 11 gaseous elements that is hydrogen nitrogen you can write down the symbol hydrogen nitrogen oxygen chlorine chlorine and the noble gases what are noble gases we have what are noble gases we have xenon is x e n o n okay helium neon argon krypton xenon redden right plus the five elements i told you hydrogen nitrogen oxygen chlorine chlorine and these six elements exist in gaseous halogen the physical state of halogen you must remember right i told you chlorine chlorine our gases bromine liquid and iodine is solid now we'll have the we'll must have the understanding of periodic table here which is very important so i'll show you the periodic table first serious okay so you must have the understanding of the entire periodic table see this is atomic number one then two three four five six seven eight nine ten eleven twelve thirteen fourteen fifteen like that okay this group that you have here the classification of elements you see this is s block first and two two these two are s block if you see here we have 10 groups from this point to this point we have 10 groups here from this point to this point and this is d block d block this has six groups from this point to this point you see and this is p block we know p sub shell can have how many electrons maximum p sub shell can have how many electrons maximum six electrons so you can have you can have np1 configuration np2 np3 np4 np5 np6 so since we have six different configuration that's why we have six different groups could you write down the electronic configuration for boron five electrons it is 1s2 2s2 2p1 see group 13 this one ca 1a 2a 3a 4a 5a 6a 7a 8a right so either you can say in terms of a and b like we had in a mender leaf preditable i told you it the groups are divided into two categories one is for normal elements and one is for transition so transition elements are b you see this it is 3b 4b 5b 6b this group is 3b 4b 5b 6b and so on this group is 1a 2a then it is 3a 4a 5a and so on okay this a a term if you see here 3a means there are three electrons in the valence shell okay i'm just you know giving you the idea of it like what all things you can conclude from this suppose you have an an we have an elements belongs to seven a group it means in its valence shell we have seven electrons you can check this i'll show you i said what elements belongs to seven a group suppose they are fluorine belongs to 7a write down the electronic configuration of fluorine and tell me the electrons in the outer most shell if you write down it is 1s2 2s2 2p 5 9 electrons you see the outer most shell is not 2p outer most shell is second two which contains two sub shell s and p the total number of electrons are five plus two seven how many of you understood this no doubt so similarly if you know the groups 3a 4a 5a 6a 7a you can directly say this is the number of electrons in the outer most shell like you see boron is 3a so it must have three electron in the outer most you see this configuration three electrons clear all of you please type in clr if you get it tell me fast quickly okay thank you another thing is what this is one thing that you can conclude another thing when you write down the configuration 2s2 2p1 right so p1 means it is the first group of p block p2 means it is the second group of p block p3 third group p4 fourth group for example you see boron is 2p1 belongs to the first group of p block this is the first group for carbon if you draw carbon has six electron right so in the last it would be 1s2 2s2 2p2 2p2 the second group of p block this is 2p3 third group of p block fourth fifth and so on all the elements you can consider like this you see one more thing i'll tell you p1 p2 p3 p4 you understand that how only six group by only six group we have in p block because we have only six different p6 correct now this is the outer most shell two and two so this outer most shell represents the period of that particular element like you see boron belongs to what second period you see this is the second period boron so this outer most electronic configuration is the outer most shell represents the period of that element right suppose you have i'll ask you what is the outer most electronic configuration of gallium the outer most electronic configuration of boron is 2s2 2p1 the outer most electronic configuration of carbon is 2s2 2p2 for nitrogen it is 2s2 2p3 2s2 2p4 2s2 2p5 2s2 2p6 because all these elements belongs to second period so their shell should be second only the outer most shell with respect to this particular information if you try to write down the outer most electronic configuration of gallium right so this would be i'll tell you gallium belongs to which period could you tell me gallium belongs to which period fourth it is two three and fourth since boron has 2s2 2p1 so outer most electronic configuration of gallium would be fourth period 4s2 4p1 if you want you can draw you will get the same configuration 4s2 4p1 for aluminium if you write it is 3s2 3p1 so for the same group all elements will have similar outer most electronic configuration number of period will be changed but the number of out electrons present in the outer most shell that won't change it is 2s2 2p1 3s2 3p1 4s2 4p1 5s2 5p1 6s2 3p1 and so on could you tell me this one what will write the outer most electronic configuration of silicon the outer most electronic configuration of silicon yes it is 3s2 3p2 because carbon is 2s2 2p2 so it is 3s2 3p2 4s2 4p2 5s2 5p2 and so on what about this bromine outer most electronic configuration tell me guys bromine I want you to respond all of you in this bromine outer most electronic configuration 4s2 4p5 ok because chlorine is 2s2 2p5 chlorine would be 3s2 3p5 bromine 4s2 4p5 5s2 5p5 so this is how we can easily understand the outer most electronic configuration of any elements ok now another thing you see this is true for entire irritable here also what is the outer most electronic configuration of helium sorry hydrogen hydrogen 1s1 could you tell me for cesium what would be what it should be cesium what it should be 1 2 3 4 5 6 first period 1s1 6th period 6s1 right so 1s1 it is 2s1 3s1 4s1 5s1 cesium beryllium is 2s2 second period 2s2 this would be strontium strontium would be 5s2 2 3 4 5 like this we can have the idea of outer most electronic configuration of any elements clear tell me tell me guys very important if you're comfortable with periodic table it is very easy for you to understand this chapter and it helps you in dark chemistry tell me did you get it all of you now the next thing see we have classified the elements in blocks s block p block d block this to our f block okay we classified the elements in block my question is based on what category okay it is based on the last electron goes into which suction if the last electron goes into s suction it is s block elements if the last electron goes into p suction it is p block elements d suction d block elements f suction f block elements like you see for these two group the last electron goes into s suction only so that's why these are s block elements you can write down the electronic configuration of any elements you'll get the same thing here also you see for all these elements if you write down the electronic configuration the last electron always goes into p sub shell and hence we have p block elements d sub shell d block elements is it clear correct so that's also you can understand in s block we can have only two possible configurations one is s1 configuration other one is s2 that's why we have only two groups here one and two s1 and s2 if you talk about d block so d block can have how many how many electrons maximum in d sub shell how many electrons we have maximum d sub shell we have 10 electrons so the possible configuration is what d1 d2 d3 d4 till d10 yes so we can have 10 groups corresponding to each configuration so this one is d1 d2 d3 d4 and it goes till here zing that is d 10 configuration clear right that's why we have two groups here then we have 10 groups and then again we have six groups total 18 groups we have here right 18 groups and seven periods now you have the idea of periodic table how it it is arranged what all things you can conclude did you get the idea of it tell me yes or no you have to yes i'll do that you have to just sit with this periodic table okay google it take a picture if you do not have book and then you analyze it once or one or two you want like no once or twice you have to do this then you will have the idea okay what i said first of all i just go one by one in this the elements are classified in blocks why in blocks because it depends upon the last electron goes into width sub shell if the last electron goes into s sub shell it is s block d sub shell so d block p sub shell to p block f sub shell to f block right so we have here two s block groups right group one and group two we have two s block groups why because we have only two configuration of as possible one is s one other one is s two finished similarly we have 10 d block groups because d sub shell can have 10 electrons so we can have d1 to d10 10 different uh no possibilities okay so we have two groups s block then 10 groups d block and then six group p block okay this is how it is arranged extreme left we have s block elements extreme right we have p block elements in between the two we have d block elements okay now next thing that all these groups has one specific outermost configuration like if you have first group its outermost configuration is s one period can be anything one s one two s one three s one four s one like that okay first group outermost configuration is s one second group outermost configuration is s two and s block is over if you talk about p block in p block the first group that we have p1 outermost configuration it is ns2 and p1 then ns2 and p2 ns2 and p3 ns2 and p4 ns2 and p5 ns2 and p6 okay if you see these groups and all right in terms of a and b then the number before a and b that is written here it is the number of electron present in the outermost shell right like one a one electron in the outermost shell two a two electron in the outermost shell three a three electron in the outermost shell four a four electron in the outermost shell if you talk about 13 14 15 16 it is simply it is 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 correct so this number if you see group 13 group 14 15 elements if you have this number the subtract 10 from that you will get the number of electrons in the balance sheet so basically let's not make it complex much okay there are so many information i can give you after this also but a little bit of idea if you are getting 40 percent also it is fine for now okay but you have to sit back with the priority table and you have to think on it like how the electronic countries and other things changes and this is how the priority table is okay that's fine 50 60 percent is more than enough but again you have to revise it before the next class okay in fact i would suggest that all these priority table you know you must revise the priority table before every class just go through once okay you have a better idea of it it's very important okay right another thing is what you see the atom i'll just write down one simple thing here what is the atomic number of hydrogen one atomic number of lithium three then 11 then 19 then 37 and then 55 and then 87 the last one is 87 here usually what happens yeah correct correct answer you see in sodium also the last electron goes into s sub shell no that's why it is s block elements three represents the period third period you see there now the important thing i would like to mention here is usually what happens we remember the atomic number of these elements which are there in the top of the priority table yes or no but do you agree with me we usually memorize these elements atomic number which is there on the top right but for exam you should at least know the atomic number till zinc that you must remember if you memorize till krypton it's fine but till zinc you don't have any choice you have to memorize atomic number till zinc right that's one thing sometimes if you want to have the atomic number or one if you require atomic number of any lower elements then how do we do that so for that we have a certain pattern that you can understand easily like you see for your reference i have written the atomic number of these elements 13 11 19 37 55 and 87 if you look at the difference here the difference here is you see this is it is two then eight then eight then 18 then 18 and then 32 the same pattern will follow in all of the group except group 18 group 18 will discuss it separately let it be okay difference is 28 8 18 18 32 okay i'll write down in the bottom for the first group group one difference is two eight eight 18 18 32 is the difference we have means what suppose you know the atomic number of hydrogen you add two you'll get lithium three you add eight you'll get sodium 11 you add eight again you'll get potassium 19 you'll add 18 rubidium 37 you'll add 18 55 cesium add 32 87 prancing this pattern is true from here also beryllium to magnesium the gap is eight magnesium to calcium the gap is again eight calcium to strontium it is 18 this is also 18 and this is also 32 okay so suppose what is the what is the atomic number of beryllium could you tell me atomic number of beryllium tell me atomic number of beryllium guys four right so if you do not memorize suppose magnesium and suppose beryllium also if you don't remember you know the position right so hydrogen is one helium is two lithium is three beryllium is four like this also you can do so once you know this beryllium you add eight this is 12 you add eight it is 20 you add 18 it is 38 you add 18 it is 56 you add 32 it is 88 did you get the pattern here yes tell me did you get the pattern press on right so this is the this is the these numbers here again listen to me carefully here these numbers 288 18 18 32 these numbers are called the magic number for group one magic number for group two we don't have two here but it is 8 8 18 18 32 and this is true for all the p-block elements except helium the magic number for group from for group 2 group 13 group 14 group 16 group 17 group sorry group 2 group 3 sorry what did I say group 2 group 13 group 14 group 15 group 16 would send it group 2 and group 13 to group 17 the magic number is 8 8 18 18 32 only we have slight change in case of p-block elements sorry this one inert gas helium is two and then it is 10 so we have eight here not two here we have two here we do not have two two eight and then 18 crypto is 36 and then it is and then it is 54 and then it is 86 so gap if you see here it is eight it is eight it is 18 it is 18 and it is 32 that's 8 8 18 18 32 see here 8 8 18 18 32 so it is same for this also for this also you can consider the position is this 1 s 1 1 s 2 but still this gap is not two here okay so this kind of pattern you must analyze you must remember this helps you in finding out the atomic number of any element in the exam if you forget I would suggest in market or in amazon any other you know of merchant you see you can buy a very large no size periodic table do all these you know all these stubble everything over there and you can stick this onto your wall right wherever you you know study or wherever you sleep wherever you know usually spend your time in the house then the wall you can paste you can stick it so that if you just you know go through it once if you just look at it once in a day you will have this in your mind in the exam you could easily visualize the periodic table the entire periodic table that helps you a lot did you get it yes no doubt in this okay so I guess you all have understood what is you know how the elements have been classified in the blocks what is the reason for that okay and what are the different blocks we have electronic configuration you got the idea okay now there are various terms that we use right different types of elements we have in this that will start after the break okay normal representative elements typical elements okay bridge elements diagonal relationship all these will see after the break correct take a break now we'll resume the session at 645 okay yeah 645 we'll resume take a break now okay hello guys there okay so so there are various you know classification of elements we have that you write down classification of elements the first type we have here is normal or representative elements normal or representative elements write down these are the elements belongs to these are the elements belongs to s or p block these are the elements belongs to s or p block except noble gas all elements belongs to s and p block except the noble gas normal or representative second one typical element write down these are the elements these are the elements which shows the property of these are the elements which shows the property of parties of other elements properties of other elements belongs to belongs to the same group these are the elements which shows the property of all other elements belongs to the same group. So typical elements are elements of third group. These are the elements of third group, not the second one. Elements of group three, third group. Like we have sodium, magnesium, aluminum, silicon, silicon, phosphorus, sulfur, etc. Sodium, magnesium, aluminum, all third group elements you can consider. Sorry, third period. I'm sorry, my bad. Third period, yeah. Third period. Okay, so elements of third period represents the property of the other elements belongs to the same group. Like sodium represents the property of alkali metals, first group. Right, phosphorus represents the property of the nitrogen family, right, that group. This thing here. Next slide down, bridge elements, bridge elements, right down. Typical elements are the elements which represents the property of the other elements belongs to the same group. Other elements belongs to the same group, not period here, right, belongs to the same group. Examples are the elements of third period. Examples, elements of third period, like we have sodium, magnesium, aluminum, silicon, phosphorus, sulfur, etc. The third one, we have bridge elements. Write down the elements which act as a bridge, the elements which act as a bridge between two different group elements. The elements which act as a bridge between the two different group elements are called bridge elements. For example, you see, if you talk about sodium, magnesium, and copper. Sodium belongs to 1A group. This belongs to 2B group. This is 1A, this is 2B group, and magnesium present in between these two. So this is the bridge elements. The first definition you have to keep in mind. Another example is potassium you take, calcium you take, and silver. Potassium is again 1A, silver is 2B, and calcium present in between the two. So it is a bridge element of the two. The next one is the diagonal relationship. Some elements belong to second period. Some elements belong to second period shows similar behavior with the elements of third period. Okay, again I am repeating. Some elements belong to second period shows similar relation with the elements of third period, which are present diagonally opposite to them, which are present diagonally opposite to them, are called, sorry, diagonally opposite to them, are said to have diagonal relationship. Again, I am repeating this. Some elements belong to second period shows relationship with or shows similar behavior with the elements of third period, which are present diagonally opposite, which are present diagonally opposite to them, are said to have diagonal relationship. This one is important. Like you see, if you look at the position here, we have lithium, sodium, beryllium, magnesium, then we have boron, aluminium, calcium, silicon. So left to right, you have to go diagonally. Like you see this one, this one, this one, this one. Okay. These two elements are observed to have similar properties. What all properties we'll discuss later in this chapter. But these elements are said to have similar properties and this we call it as diagonal relationship. Because the elements are present diagonally to each other. Like this we don't define. Okay. Left to right to go. That is a diagonal relationship. Okay. Fifth point. Transition element. Transition element. These are the, these are the D block elements. These are the D block elements which has unpaired D electron. These are the D block elements which has unpaired D electron. Okay. Which has unpaired D electrons in their ground state or excited state. Right. These are the D block elements which has unpaired D electrons in their ground state or excited state. Like for example, you see if you take an example of scandium. Okay. Or titanium. Okay. So, could you write down the electronic configuration of this? All of you, please. That's what I want you to identify it. What is the position of titanium? No, it's not. Titanium is after scandium. Yes, 22. That's right. Titanium atomic number is 22. Now you write down the electronic configuration. And I want you to write down the electronic configuration of zinc also. We have discussed it. Okay, correct. What about zinc? Yes. So, the electronic configuration here is 1S2, 2S2, 2P6, 3S2, 3P6, 4S2, 3D, 2. Okay. For zinc, it is 1S2, 2S2, 2P6, 3S2. 3P6, 4S2, 3D, 10. In short, in terms of argon also, we can write. Okay. This 3D electron you see, 3D has five orbitals. One, two, three, four and five. And it has two electron present according to Hansel. And this has all the five orbitals filled, completely filled. Right. So, transition element, the definition is what? D-block elements which has unpaired D-electron in their ground state or excited state. Right. You see in zinc, all D-electrons, we are talking about D-electrons here. This electrons and these electrons. In zinc, these electrons are paired. This one is not paired. So, this one is the, this one is titanium. It has unpaired D-electron. So, this is the typical element. Sorry, not typical transition element. This is the transition element. Right. This zinc is not transition element. It is D-block element. So, transition element comes under D-block only. So, this is the difference between the two. Right. You must keep that in mind. D-block elements, right? Which has unpaired D-electrons are called transition element. Which one, Auro? Hansel, you know, Auro? Could you think of Hansel over here? Okay. Understood. No. Because of Hansel only. The pairing is not possible. All the electrons are, unless all the electrons are singly occupied. No. No. We can't do that. After 3D6, also it is transition. 3D7 also is transition. Whenever you have unpaired D-electron, it is transition. Except 3D10. Yes. So, all transition elements are D-block elements. But all D-block elements are not transition element. The vice versa is not true. Right. Transition elements are D-block. But D-block are not transition elements. Okay. So, we have Zinc, CD and HG. For these three elements, the D-orbitals are fully occupied. D10 configuration it has. That's why these three are D-block elements. All other elements are transition. Right. See, one more thing I'll just show you here. Zinc, you know the configuration this. CD, HG, you see, Zinc, Cadmium and HG. These elements belong to the same group. I'll show you. You see this. Zinc, Cadmium, HG. So, if it is D10, this one is also D10. This one is also D10. So, this is the one that I have written. The Zinc, CD and HG are D-block elements, not transition elements. This is the application of the pattern that we learned few minutes back, half an hour back. Okay. If this has D10 configuration, this also has D10 configuration. This also has D10 configuration. Hence, they belong since they belong to the same group. That's why these are D-block elements, not transition elements. Did you understand this point? Yes. So, all of you write down all transition elements are D-block elements, but vice versa is not true. Next, write down inner transition elements. Inner transition elements are F-block elements. That is it. Inner transition elements are F-block elements. Write down inner transition elements. Inner transition elements are F-block elements. F-block elements, we have two series in this. Two series. one is we have four f series four f series means the electron goes into four f uh sub-ship right four f series it starts with cerium atomic number 58 and goes up to lewtium lu lewtium atomic number 71 okay this has 14 elements because f can have 14 electrons so this series has 14 elements right and this cerium to lewtium this we call it as lanthanide series lanthanide series okay the second series we have that is five f series five f series it starts with thorium th atomic number 90 and goes up to lewtium atomic number 103 this also has 14 elements also has 14 elements right and this we call it as actinide series lights and lanthanides remember always lanthanide starts with cerium 58 goes up to lewtium 71 actinides starts with thorium goes up to lorencium 103 did you copy this yes tell me now you see i'll show you in the priority table i'll take the new one because again you know series i'll show you here okay you see here this is barium i'll write down here so that you can understand this is barium and its atomic number is 56 then this is 57 and this 57 is lanthanum it is 57 is lanthanum after 57 the atomic number should be if you see here it is 37 38 39 40 41 like this it goes 37 38 39 40 41 like this it goes but here it is 55 56 57 but this one is 72 after 57 we have 72 similarly this one is 87 this one is 88 this one is 89 but here we have 104 so 40 elements there's a gap here 14 elements not 40 14 elements there's a gap here these 14 elements it is shown over here you see this is 57 this is lanthanum l a n t h a n u m lanthanum this one is actinum a c i t i nu m actinum right this one is cerium this is atomic number 58 you see this is cerium atomic number 58 and this is lewtium atomic number 71 so what happens after this lanthanum the electron starts fill into 4f orbital if you look at the electronic configuration for this one f sub-chill this one is 4f 1 4f 2 4f 3 4f 4 till 4f 14 right so from cerium to lewtium this series we call it as lanthanum series or lanthanides because it starts after lanthanum that's why it is lanthanides so it is always you know you know the students are confused in this one that lanthanides starts with lanthanum no lanthanum is not a part of lanthanide series okay since lanthanide starts with cerium because the f sub-chill has one electron here it starts filling here right that's why the series f series starts from cerium from cerium to lewtium that's why the lanthanide series starts with cerium and goes up to lewtium if you talk about 4f series this is the same thing it is actinum it starts after actinum this is 90 and this is 103 and this is 5f series okay so this one is actinides this one is lanthanide they don't ask any question on this just you should know what is the first element and last element for the two series lanthanides and actinides yeah okay so i want you to do some you know revision work on this predatory table whatever i have discussed today right you must revise this if you have the predatory table with you find otherwise you can easily get it online okay google it you will get the predatory table open it and then you can check okay all these things very important if you have a better understanding of predatory table it's very easy for you to understand this particular chapter it helps actually an entire chemistry but especially in this chapter it will be very comfortable okay so this is the few properties we have discussed for you know initial properties we have discussed now for a given elements how do we predict the period group and block for that particular how do we predict the period group and block right down the prediction of prediction of period group and block right usually what happens electronic configuration will be given in the question is given now in this what happens the period is period is the maximum value of maximum value of n you can easily find out period for any element in the electronic configuration maximum value you check that is the period okay sub shell that is block sub shell means spdf right sub shell or block b is the sub shell in which sub shell which takes takes the last electron that's what we have discussed from s block p block d block the last electron enters into s sub shell it is s block so it is the last electron group we have certain formula here for s block write down group you have to find out this two is done for s for s block the formula is if the configuration is this inert gas configuration and ns1 like this it means it is group one any doubt in this if you have inert gas configuration and it is ns2 then it is group two s block we can find out this for p block what we do for p block we'll write the group is equals to 12 plus number of electrons in p sub shell in p sub shell outermost p sub shell okay we can write down this 12 plus number of electron in p sub shell why 12 because you see if it is 3p1 right so 3p1 is this one 3s2 3p1 is aluminum so we have 10 electrons here plus 2 so this 10 plus 2 12 you have to add means in this 3p1 1 plus this 12 then it comes to be 30 that's why we have that formula 12 plus number of electrons in outermost p sub shell we'll do some example you will get it if it is d block if it is d block then group will find out group is equals to 2 plus number of electrons in n minus 1 d sub shell n minus 1 right pallet image shell n minus 1 d sub shell not the last one right suppose if you write down 1s2 2s2 2p6 3s2 3p6 4s2 3d1 right so here the outermost shell is 4s not 3d electron goes into 3d orbital after 4s because of its energy but outermost shell is fourth shell so outermost shell is fourth this is n so n minus 1 is what 3 so one electron we have to consider okay this is what it means number of electron in n minus 1 d sub shell if it is f block write down this if it is f block for f block the group is always 3 always 3 because you see this again periodic table this is the f block right and f block is present here you see this present here this is fourth one and this is third group we have here f block third group so f block is you don't have to do anything if it is f block the group is always 3 pop it is down and look at this example 1s2 2s2 2p6 3s2 2p6 you need to find out the period then we have block and then we have group 1s2 2s2 2p1 x e 4f0 5d0 6s2 krypton 4d10 5s2 argon 4s2 3d6 find out the period block n group see in the first one the period is the maximum value of n that is 3 you won't have any confusion in this period right 3 last electron goes into p sub shell the block is p and for p block we know the formula it is 12 plus the number of electron in p the group is 18th group here any doubt in this tell me yes guys please it's gone okay this one the period is 2 the block is p and it is 12 plus 1 that is 13 group boron this one is maximum value of n period is 6 block is s and if it is s block n is 2 configuration we have so it is group 2 right period is 5 block is s is it s block it is d block because electron goes here it is like 4s2 and 3d like 4s first and then 3d i have written it this way but first electron goes into 5s and then it goes into 4s energy also if you see the 5s energy is 5 n plus l value and this one is 7 right this has more energy fills later right so it is 5 block is d and for d block we have the formula that 2 plus 2 plus number of electron in n minus 1th d sub shell that is 10 and is this n minus 1 is 4 10 so 2 plus 10 that is 12 this one again the same thing right so this is 4d 2 plus 6 that is 8 did you understand this guys respond any doubt all these questions you can easily do if you have a better understanding of electron this periodic table right you can easily use that but actually the formula if you memorize you can save your time in the example that's why the formula is given okay fine guys thank you so we will continue from this next class okay we'll see some more properties next class okay yeah take care guys yeah thank you bye