Periodic Properties and Atomic Radius

Hello friends, today we will talk about periodic properties. This is the fourth video of periodic table in which we will start discussing periodic properties. Periodic properties are those properties which after some regular intervals repeat one trend. repeat your trend after regular intervals increase after regular interval decrease in a pattern they are called periodic property so the first periodic property we are going to see is given in your book and is very famous for you and that is atomic radius so the conventional definition of atomic radius is that suppose here is a nucleus and here are the shells so the distance of the electron of outermost shell the distance of Electron from the nucleus. Which electron? The electron of the outer shell. Its distance from the nucleus. This is called atomic radius. But this definition is correct for 9th and 10th class. But if you have come to higher class, then this definition will be wrong. Because you have read the atomic structure chapter that electron is a wave. Electron is not a particle, electron is a wave. If electron is a wave, then electron will be moving like this. We don't know the exactly defined path of electron. We are not sure about the exact path of electron. Since electron is a wave, the boundary of atom is not defined. So this definition will be wrong. Which definition? Write it down if you want. Which definition? That the distance of the electron in the outer most shell from the nucleus of the atom is called atomic radius. This definition will not be valid because of this point that the boundary of atom is not defined because electron is a wave. So, because of all these problems, we started measuring atomic radius in a new way. How? We measured atomic radius in bonded state or in interaction state. We have stopped measuring in free state, we will not measure individual atoms in bonded state. So, the methods of measurement in bonded state there are many methods which you have to read, which are in your syllabus. First one is covalent radius, that when covalent bond is formed, then what will be the radius? Now, it is fixed after the bond is formed. Second one is, we have, guys, the Wander-Wall radius. The third one which we will read is is metallic radius. And the last one we have to study is ionic radius. First, we will understand what are these radiuses and at the end we will also study what is their trend? How they vary? Which variation? Along the period and down the group variation. So, first we will understand them. The definition of atomic radius is not valid. Now, we have to understand this type of atomic radius. which is in bonded state and not in free state so that in bonded state, the boundary of atom will be defined covalent radius, Wonderwall radius, metallic radius and ionic radius so let's start with covalent radius a very good morning, a very good afternoon, a very good evening and a very good night whenever you are watching my video I am Alak Pandey, my channel is physics keep on reading, enjoy, it is fun it is morning time, time is 11, I think and today is 17th June and we are going to study periodic table lecture no.4 so let's see what is a covalent radius covalent radius, you had the idea of atomic radius covalent radius, you understand covalent bond suppose there is an atom A and there is an atom A and they are covalent bonds so how do covalent bonds are formed? by sharing of electrons you must have seen how electrons are formed by sharing of electrons, one electron cloud is shared with another electron cloud In this condition, distance of the previous nucleus to the second nucleus is called distance AA If you halve this distance, that is called covalent radius So what is the method of removing covalent radius of an atom? Take one more atom like that, form its covalent bond with it After making that covalent bond, the distance between the two atoms in the center to center half of that is covalent radius. Clear? Very easy. Very clear. Now you have understood that two similar atoms form a covalent bond between them after forming a bond, the distance between them there is a name for this distance distance AA you will read the bond length what will you read? bond length so, the half of this bond length is called covalent radius now, what is the good question in this? the good question is that suppose atoms are not similar atoms are different here, what will happen to this distance and this radius? same because atoms are same Assume atoms are different. Atoms are different. Is covalent bond formed in different atoms? Yes, it is formed in different atoms. Have you seen the example of HCl? Covalent bond can be formed in different atoms as well. Similar to H2, hydrogen and hydrogen. This is the example of H2. Now what to do in different atoms? There are two conditions in different atoms. If electronegativity is same. Electronegativity is same. How will you understand this? Understand this as the power of attracting electrons. If they are same, means the behavior towards electron is same One is saying we need less electron, so the other is saying we need less electron One is saying we need more electron, so the other is saying we need more electron Means the behavior towards electron is same, that is Electronegativity So suppose Electronegativity is same for both And there are two different atoms, one is A and one is B And between them, this covalent bond is formed Now, the distance A-B which we can call as Bond length that is equal to radius of A plus radius of B but note here that A and B radius can be equal or not but here definitely both have same radius so here I will give you a simple question that is the Bond length in HCL is same or not HCL or any other where electronegativity is same like in methane, CH4 Here, the electronegativity of carbon and hydrogen is same. The electronegativity of carbon and hydrogen is same. They are of the same nature. So, we will be asked, is its bond length this much? If the radius of carbon is this much, then we will be asked, is the radius of hydrogen this much? Then you will get the problem out. The second condition is, if electronegativity is different. If electronegativity is not the same, then what to do? Electronegativity is different means, one has more electronegativity and one has less. The more electron, the more the electron will attract. The electron clouds will enter the system. Let's assume that the electronegativity of A is the same as that of B. If A is the same, then the system will be like this. B, A. The electron clouds will shift towards A. The bond length, which we call the distance between A and B, this distance between A and B will be equal to RA plus RB minus 0.9 multiplied by psi A minus psi B. note the formula, I have written it in a notebook let's move from here. what is written? distance between A and B let's write the formula of electronegative difference here. distance between A and B ball length is equals to RA plus RB minus 0.9 chi A minus chi B. Now why did we get this term minus? It is a matter of thinking. It would have happened that the electron cloud would have come inside. That means the radius would have been reduced a little. The electron cloud would have come inside. For this, we have put minus here. Now what is the need here? The need is the electronegativity of A and B. So if electronegativity is different in different atoms, then the minus symbol has to come. If it is the same, then simple, we have to get RA plus RB. Now the question can be asked, what is the radius of hydrogen? The answer is the bond length of HCl. The bond length of HCl will be given, the radius of hydrogen will be given, the electronegativity of both will be given, and the radius of chlorine will be asked. For example, if we take the case of HCl, then the electronegativity of both of them is different. So, the electronegativity of both of them will be given, and the difference of electronegativity will be given. The radius of one will be given, and by adding any variables, it will make one variable disappear. So, for that you should know this equation. So, this was Covalent Radius. Covalent Radius is one half of the distance between the centers of two combining atoms. If the atoms are same, if they are different, then the distance between A and B is RA plus RB. And if the electronegativity is also different, then you can use this formula to find the covalent radius of both the atoms. So, this was our covalent radius. Now we have to study the second type of radius Second type is Wonderwall radius What is Wonderwall radius? Covalent bond is known to be shared by electron Wonderwall force is in neutral molecules Not in bond molecules Wonderwall force is in any bond You are learning since childhood that the molecules have intermolecular forces of attraction The molecules, the molecules, suppose there is a molecule here Not an atom, a molecule, AB, here also there is a molecule, AB This is a molecule These molecules attract each other You are learning since childhood the intermolecular force of attraction That intermolecular force of attraction is the Wonderwall force That intermolecular force of attraction, which we learn since childhood, what is its name? Wonderwall force So,Wonderwall force When will the bond of the boundary wall be formed? Without any bond, sorry, boundary wall radius When will it be formed? When will we talk about boundary wall radius? When there is no bond Suppose, here is one molecule of hydrogen Here is another molecule of hydrogen Now there is no bond between them Only intermolecular force of attraction is there between them At this time, the distance of their center to center Distance between hydrogen and hydrogen molecule Divided by 2 is known as Wonder wall radius So where to apply wonder wall radius? In atom or molecule? In molecule Two molecules which were as close as possible came in front What did I say? Two molecules which were as close as possible came in front in closest approach Can't come close with this If you bring close with this they will run away If you bring close with this they will be far away Nucleus will have repulsion in nucleus Electron will have repulsion in electron As close as possible came in front at that time, half of the distance from center to center is Wonder Wall Radius so now it will count without any bond count is Wonder Wall Radius clear? let's see another example and explain suppose this is a molecule A,B let's make one more here A,B someone told us that we need Wonder Wall Radius of B Wonder wall radius of B. So, we have brought the close from both the molecules. Now, see the distance between B and B. The distance between B and B in the closest approach. Divide by 2, that is, Wonder wall radius of B. Nobody told us that we need the Wonder wall radius of A. So, the distance between A and A, measure the distance between them. Distance between A and A, divide by half. Wonder wall radius of A. Clear? Wonder wall radius is found in molecules. In molecules, different atoms are found. So, the approach I am telling you is like this. When B is found, B is placed in front of B. When A is found, A is placed in front of A. Take distance from closest approach and divide by half. It will be very clear. The biggest use of these is in inert gases. Ok, tell me what are the inert gases? What are the noble gases? Do they make bonds? No, they don't. Right? In most of the cases, noble gases are bonds. That's why they are inert, they don't react with anyone. So, the radius of noble gases is the bond-revolved radius. They won't react, they won't make bonds. So, without bonds, as much as they can get close to us, for example, I took helium here and helium here. As much as they can get close, I took the distance of their center to center, distance of helium to helium, Divide by 2, that is radius of helium. And which is this radius? Wonder wall radius. Someone may ask you, what is the radius of helium? Listen to my question carefully. What is the radius of helium covalent? We cannot find it. Because it will not form a bond. It will not form a bond. What is the radius of helium? Wonder wall radius. So, wonder wall radius is very very important for inert gases and noble gases. So, this was the second type of radius. Now, I am going to ask you a question. Which radius will be bigger? Wonder wall radius or covalent? Think before you reply. Which radius will be bigger? Wonder wall radius or covalent radius? Think before you reply. See, in Wonder wall radius, you can see that there is a gap in the middle. So, this radius will definitely be bigger. What happened in covalent radius? Overlapping. In covalent radius, the overlapping radius will be less and this radius will be more. So, Wonder wall radius is always greater than covalent radius. We will put this in the notes. very very important, I will teach you in exception also in one place there will be exception and there you will get its explanation you will get example that wonderwall radius is always greater than covalent radius covalent is overlapping in wonderwall atoms are 2 then definitely this radius will be bigger I think you understood what is the border wall radius and where it is used the lecture which will make notes in my lectures will be more beneficial I give very lengthy lectures in very short time if you go to take this lecture in Kota Vata Coaching then you get at least 10-12 lectures I condense those lectures in 7-8 if any of my student is studying in Kota or if any of my student is watching my video then you tell me where is the shortfall topic is left out. So, you can read from any teacher. The topic is the same but I have to condense it. Because we are on an online platform, we cannot afford 2-2 hours of videos. So, it is important that you make notes. I am telling you those things quickly. I am not leaving out any talks. Let's move ahead. Today, you will see my exceptions. Then, you will see my exceptions from the previous table. Then, you will understand. Anyways, let's move ahead. Now, we will talk about the third type of radius. That is, Metallic Radius. Brother, Metallic Radius As the name suggests, it should be metal, then also it will be metallic radius Metal does not make covalent bonds, ionic bonds, coordinate bonds Metal has a different type of interaction For example, if I tell you that you have an iron rod What is there in that? Iron, iron, iron, iron, iron, iron, iron, iron How? 1D, 2D or 3D? Tell me, 1D, 2D or 3D? 1D, 2D or 3D? In 3D, right? Iron rod is 3 dimensional, iron is everywhere Covalent bond cannot be made, for covalent bond we need one metal and one non metal Ionic bond also cannot be made, in that metal and non metal Covalent bond has sharing of electron, metal will not share electron Coordinate bond has one donate and one donate, nothing like that will happen So here a new type of bond is made, which we call as metallic bond So how metallic bond is made, you know that metals have free electrons Metals have what? Free electrons, everyone has read it So free electrons of metal keep floating on the surface. Suppose there is a metal plate here. Suppose I have a metal plate. Now electrons are floating on that plate. Now those electrons will attract the next metal as well. How will they do it? Suppose this is an atom and this is another atom. Let me explain two atom examples. This electron is of this side and this is of that side. Here is the nucleus and here is the nucleus. This electron is very free. It is moving here and there. So this electron has also held this nucleus and this nucleus and also held this nucleus and this nucleus You can understand that electron is flowing like glue Right? You can understand that electron is spread like glue and all the nucleus are stuck all the free electrons This type of bonding is called as metallic bonding or lattice of metal The structure of metal is like this in which there are close packing structures HCP, CCP, FCC you have to study in 12th class, if someone has studied then he must have seen it so this bonding in which metal electrons attract the nucleus and keep bonds or electrons keep flowing and sticking, that is called metallic bonding at this time, the distance between two atoms in the center to center of metal is divided by 2 that is metallic radius there is no other story to tell about it metallic radius is to make lattice of metal, make crystal of metal metal in crystalline form or amorphous form? crystalline form amorphous is that which does not have any shape or size which can be changed metal is in crystal form or defined shape? so in defined shape, take the distance between two atoms and divide it by 2 that is metallic radius my last question is now tell me, covalent radius wonder wall radius wonder wall radius and metallic radius, which is the largest and which is the smallest, arrange it completely let's do it by ourselves I think the largest is going to be the wonder wall because the metallic was like this, the wonder wall was like this and the covalent was like this this is covalent, this is wonder wall and this is metallic so the largest is going to be the wonder wall, definitely, so the wonder wall radius is the largest after this, do this, think and say this is the smallest, it is overlapping, after this, metallic radius and after metallic, covalent so this is given in books you must have understood how it came the biggest one is underwall because there is no bond after that metal, there is no overlapping after that covalent because overlapping has also happened so guys these were very basic things in which we have explained in different ways Let's talk about different types of radiuses of atoms. Now we will talk about their variations. We have understood three types of radiuses. Which are covalent, Wonderwall and metallic. The biggest one is Wonderwall, then metallic and then covalent. Let's talk about variation of atomic radius. How it will vary? You know what are the variations to be studied? One is along period and another is down the group. In group, we study from top to bottom, top to bottom. In period, we study left to right, left to right, right to left, or right to left. I will tell you next time for sure. Promise. So left to right. Let's take any one example I always explain with second plate example Let's take second plate example Let's take lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine and neon Atomic number 3, 4, 5, 6, 7, 8, 9, 10 That is atomic number that is Z What is Z called? Atomic number What does Z tell? Number of protons where do protons go? in the nucleus in the nucleus so we call this as nuclear charge what do we call this? nuclear charge what happens in the nucleus? proton and neutron why is there a charge? because of proton so we call this as nuclear charge why is there a charge? because of proton who is there in the nucleus? proton and neutron there is no charge on neutron there is positive charge on proton suppose there are 3 protons in someone's nucleus So, how much is the total nuclear charge on it? 3 We also call it as nuclear charge Nuclear charge Ok Electronic configuration 2,1 2,2 2,3 2,4 2,5 2,6 2,7 and 2,8 See, all of them have the same number of shells The number of shells are same How many shells are there? 1,2 Here, 1,2 Here, 1,2 Here, 1,2 Here, 1,2 2,2 shells So, there is no difference from the shell Everyone has the number of orbit. So, what will be the difference? What will be the difference? The difference will be due to nuclear charge. How much will it be due to nuclear charge? Nuclear charge is due to protons. See here, the outer electron is being pulled by 3 protons. And here, the outer electron is being pulled by 6 protons. and here see this outer electron it is being pulled by 9 protons so brother its size will be small or not? think and tell me how many protons are being pulled here? 9, so when we pull 9 protons then its size will be smaller here 6 are being pulled and here only 3 protons are there So, because protons increase as they go left to right, number of protons increases. Now, what we will use for number of protons technically? Nuclear charge. So, we will say that because nuclear charge increases, what happens by increasing nuclear charge? Protons increase due to which electron gets attracted. So, what increases on electron? Attraction increases. I'm sorry. and this attraction brings the electron near the nucleus due to which atomic radius decreases so the general trend is that atomic radius decreases when it moves left to right atomic radius decreases when it moves left to right what is the reason? increase in nuclear charge then comes down the group top to bottom so there is no special story in this when it goes down, do you know that number of shells increases? everyone knows, take an example Hydrogen, Lithium, Sodium, Potassium, Atomic Number 1, 3, 11, 19 Number of Shell 1, 2, 1, 2 Shells 281, 3 Shells 288, 1, 4 Shells So definitely its size will be big 1, 2, 3, 4 and its size will be small, it is 1 shell You are seeing number of Shells 1 Shell, 2 Shells, 3 Shells 4, K, L, M, N So, the number of shells is increasing and the electron is going away from the nucleus. So, definitely size increases when it goes down. So, when it goes down, atomic radius increases with me and decreases from left to right. So, this is the world. You must have read this in 9th and 10th. The question arises with exception. You know that. You also search. You must have come to see one of my videos that where is the exception. Everyone knew this. Let's talk about the exception. First understand one thing. Along a period, nuclear charge increases due to which atomic radius decreases. Down the group number of shells increases, in this case atomic radius increases. If any property is decreasing, then it increases in this direction. If it is decreasing here, then it will increase here. If something is increasing for a longer period, then it will decrease down the group. This is opposite. Now I will show you the exceptions that you can see in the video. Now the video has started. The concept of ionic radius is going to come from here. Many people will close the video and go. So, their souls. God bless them because they left it on the main topic. Let's start with the exception story. The first exception is going to be in period no.1. The first period elements are hydrogen and helium. At left to right, the atomic radius should be decreased. But what happens is that the atomic radius of helium is greater than that of hydrogen. What should have happened is that the atomic radius should have decreased, but the atomic radius of helium is greater than that of hydrogen. Reason? The reason is very simple. What is the gas of helium? Nobel gas. What is defined for Nobel gas? Wonderwall radius. End of story, end of game. End of discussion. What is defined for Nobel gas? Wonderwall. And what is the radius of hydrogen? Covalent. So, we know that Wonderwall radius is greater than Covalent radius. We can't always take it, but we have to take it in noble gas, they don't have any other radius. Sometimes the question arises, why is the radius of Helium more than Hydrogen? When the radius should be less wherever we go. So, you can say that only Wonderwall radius is greater than Covalent radius. Same exception will come in period number 2. Period 2, Lithium, Beryllium, Boron, Carbon, Nitrogen, Oxygen, Fluorine, Neon. Should I arrange something for this? So, when we go this way, atomic radius will decrease. When we go left to right, atomic radius will decrease. So, it will decrease. Less lithium, sorry, more lithium, then beryllium, then boron, carbon, nitrogen, oxygen, fluorine. Fluorine is fine. Atomic radius is decreasing this way. But, the radius of neon is more than these. Why? The reason is this. Which radius of neon will be defined? Wonder wall. rest of the Sodium, Magnesium, Aluminium, Silicon, Phosphorus, Sulphur, Chlorine and Argon will come first because it being a noble gas only it has Wonderwall radius. it does not have covalent radius. Is that clear? So this was the first exception of Wonderwall radius that all the noble gases have atomic radius exceptionally high. Is it clear? Now let us show you an amazing exception of D block. So you must have read D block in periodic table. Where does D block start? Atomic number 21, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc. Okay? 22, 23, 24, 25, 26, 27, 28, 29, 30. So, what are you thinking? How will the atomic radius be? The expectation is that by going this way, Nuclear charge is increasing, 23, 24, 25 number of protons are increasing due to which atomic radius should decrease we were thinking like this, what were our expectations so nowadays you do that, what is that thing called? expectations versus reality so let's see reality, reality is little different what happens in reality? there is little difference in reality from here to here atomic radius decreases then from here to here atomic radius decreases becomes constant and then from here to here atomic radius increases when you read exception case then only selection will happen so in the beginning atomic radius decreases then in certain period it becomes constant then after that it increases, it doesn't decrease regularly, in reality it happens now why is this happening? this question also comes come children let's do its configuration scandium 21, if you do the configuration of 21 then 1 is 2, 2 is 2, 3 is 2 I will show you quickly, 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d1, this is it 2, 2, 4, 6, 10, 2, 12, 6, 18, 20, 21, 3d1, very good so kids, its configuration will come, of this KDM, 3d1, 3d2, 3d3 what comes in place of 3d4 of chromium, 3d5, exceptional configuration also of manganese D5 is also there, Iron is D6, Cobalt is D7, Nickel is D8, D9, D10 You know D9 is not available, D10 is available, Copper is also exceptional I have told you many times that two exceptions are in Chromium and Copper Half field is more stable and full field is more stable So, one question can also be asked that in the first D series 3D1, 3D2, 3D3, 3D4 so you can say 3D series, this is called 3D series there is no configuration in 3D series so you will say there is no D4, D9 here the question is something else that why this pattern is there see from here to here, what is happening? electrons are filling up, 1, how many came in this? 2 how many came in this? 3 it is increasing here an exceptional thing happened in d5, d5 and d6, let me show you I have taken 5, d is 5 1, 2, 3, 4, 5 and this is 6 now what is happening when 5 and 6 come by getting an extra electron here starts the repulsion of electrons as the number of electrons increases listen to me carefully as the number of electrons increases the repulsion of electrons starts Now if we repel electrons, then the size of the atom will increase. Like from here to here, electrons were less. So electron repulsion is less. But what is increasing from here? Nuclear charge. 21, 22, 23, the nuclear charge is increasing. Or you can say that Z is increasing. So from here to here, because of Z increasing, the atomic radius is decreasing. because electron repulsion is not that much what happened here? electron repulsion is there due to which it is trying to spread and nuclear charge is increasing due to which atomic radius is trying to decrease electron repulsion is there due to which atomic radius is trying to increase nuclear charge is increasing and by increasing nuclear charge and positive charge radius is trying to decrease here both the factors are fighting each other so here Z is increasing who is balancing it? electron by electron both the factors are equal to each other so neither the atomic radius can increase nor decrease what happened here is that Z is increasing a lot so much that the repulsion of electrons is not that much there are very few electrons and not much repulsion there is only one factor which is the increase of nuclear charge here electrons are increasing and repulsion is so much that it is fighting with this factor and atomic radius is not increasing nor decreasing now come forward D8, D9 Let me make D8. 1, 2, 3, 4, 5, 6, 7, 8. Now see, the repulsion of electrons is very high. Here the repulsion factor of electrons is more than the repulsion factor of nuclear charge. Here the repulsion of electrons is so high that the radius of the atom is increasing. Nuclear charge is also increasing due to which the radius of the atom should decrease. But that factor is not dominating much. as compared to electron-electron repulsion so this was the story here that in the beginning only the nuclear charge was increasing later the electron repulsion was increasing the nuclear charge was also equal neither the atomic radius could increase nor decrease in the end, the repulsion of electron-electron was the highest because the number of electrons was increasing as the number of electrons increases the number of electrons will increase as and when electron-electron repulsion will increase ok And we saw that the repulsion of electrons and electrons was so much that they expanded. So, we said that in the beginning we dominated this factor and then this factor and in between both. So, in the exam, the question arises that which one is the biggest and which one is the smallest. Suppose, we ask them to arrange and one of them gives us four elements. Any four elements, like here you are saying almost equal, it is said that compare Magnesium, Cobalt, Titanium, and Bidonium. What is happening in the beginning? It is decreasing, then it is increasing. So, there can be a confusion that the radius of zinc is increased or the radius of titanium is increased. Here it is decreasing, then it is increased, in between it is decreased and increased. So, to end all these confusions, we give you a trick so that you can remember it completely. Scandium, Titanium. Zinc, Validium, Cobalt, Nickel Remember, in Scooty, there is no Zinc Scooty, Scandium, Titanium I don't care about zinc, same with vanadium, no one in the last, this is our order, bigger, and then cobalt will come out because the order was very disturbed here so we made it like this zinc in scoopy same no one and what to write to the rest of the kids equal so note this you should remember this exception in 3D series and this order is also in 4D and 5D series 4D means the series below it 5D means the series below it this is the exception in that too there is no need to remember the order it is not being asked let's show you the next exception exception number 3 this is also inside D block very important let's understand let's assume that we have scandium yamaha lau egg, remember? this is 3D series this is 4D series this is 5D series atomic number 21 atomic number 57 next, next to this scandium, titanium, atomic number 22 T, Zara half titanium, zirconium, hafnium I have taught you all these in the video number 2 of the Pivot Table how to remember it, t is half here atomic number is 72, pay attention some elements have disappeared from here which you know that 58 to 71 where they have gone? in lanthenoids where they have gone? in lanthenoids after this next, vanadium that was new Meridiem, Noabium, Tantella Here 73, here 23 and so on Children, you are going to the downer group, so what will you expect while going to the downer group? What will you expect while going to the downer group? You will expect that the radius of the atom will increase As we asked here what will you say about the radius of the atom? You will say that the radius of the atom will be smaller than the radius of the scandium, and the radius of the uterine will be larger than that of the lanthanum You will say this only As you go down, the number of shells increases and the atomic radius increases Absolutely correct Here the trend has changed. Here the trend was titanium, bigger than that zirconium, and haplium is equal to that. It has grown from here to here, but here and here it is almost equal. Like here the same thing happened, small of meridium, new of sodium, and almost equal to tantalum. What is happening here? This 4D and 5D 4D and 5D series atomic radius is almost same. Here it didn't happen, but it started with the next element. So, you must be thinking that some story must have happened here. Some story started after 57. This is a regular trend. This is following a normal trend. Here some abnormality happened, their radius doesn't match. So, something must have happened here. Let's understand what is special about lanthanoids. After 57, the jump happened. After that, the atomic radius was almost equal. From here, the atomic radius should have increased. It didn't. so in lanthinoids In lanthenoids, that is account number 58 to 71, you know that slowly slowly slowly slowly F-sub-shell fills up. 4F fills up here. When 4F fills up, there is a very big contraction which we call lanthenoid contraction. What happens? What happens? Say with me, lanthenoid contraction. means when we move in 4F, then the size becomes very less suddenly the size becomes very less when we move in lanthanoid series, then the size of atoms in lanthanoid series becomes very less I am showing you the lanthanoid series when we move from here to here when we move from 58 to 70 in lanthanoid series, the size of atoms decreases very fast it decreases so fast that even when 72 number comes, the size of atoms remains small due to which the radius of zirconium and haemium is not equal If the number of shells would have increased, then the radius should have been higher. But due to this lanthanoid contraction, a very massive contraction, in lanthanoid, as soon as they run, 58, 71, the size of the atom becomes very small. And due to this contraction, the size of the haplium becomes small. And due to which the radius of zirconium haplium is almost equal. Or due to which the radius of 4D and 5D series, someone asks you why the radius of 4D and 5D series is equal. Why not, the radius increased from here to here, then you will say due to lanthanoid contraction. We all know what is lanthanoid contraction. So, we will have to explain. First, note that when 4D to 5D is applied, if you leave this, its idiom, uterine and latinum, after this, the radius of this and this is equal to this, and this and this is equal to this, and this and this is equal to this. Why did this happen? Because the radius had to be increased from here to here. But after lanthanum, the radius was suddenly very small, 58 to 71. And when it came to 72, the radius was small, due to which these two are almost equal. Now, what is the reason for this? So, look for the reason. Reason for kids to go to the head in a new topic in the table I will teach you all should read We call it shielding effect This is a new topic, let's add heading Shielding effect What is shielding effect? Suppose this is a multi electron system Here is This electron will repel this electron and the nucleus will attract this electron. So we can say that this electron is trying to protect the outer electron from the nucleus. These electrons have hidden the nucleus inside and are protecting the outer electron like a shield. These are inner electrons. So what do the inner electrons do? They shield. Who? outer electrons from which we shield? from nucleus, we save from nucleus we reduce the effect of nucleus this is called shielding effect where will this happen? in multi electron system who shows? inner electron this is like shield we hide the nucleus inside and don't let the effect go out to the outer electron we will understand this only then we will understand lanthanol contraction ok we have 4 subshields, S, P, D, F The most shielding effect is with S, then P, then D, then F. You will ask why? Due to their shape. S is closest to the nucleus. So, S is closest to the nucleus and keeps it pressed. F is very dispersed. How is the shape of F? Very dispersed. It is 8-fold, completely scattered. If it is completely scattered, then the nucleus, suppose F is like this. This is F. Now, what will this save the external electron? And what is S? This is S. It has closed the nucleus in itself. So it can save the external electron. So the shielding effect of S is mostly of P, D and F due to their shapes. S completely presses the nucleus in itself, saves the external electron. F cannot save it. So this is called shielding effect. So we have understood the shielding effect in the multi electron system. Inner electrons shield the outer electrons. Who are they shielding? from where? from nucleus we save from the effect of nucleus, how we save? we repel it and if we want to imagine it, we make it like a shield the biggest shield is of S, P, D and F after understanding all this, you come back why this contraction happened? why this contraction happened from 58 to 71? so the filling here 4F0, 4F1, 4F2 and 4F is the filling upto 14 there is some disturbance in between but overall trend will be same F has poor shielding effect now you saw who is the last in shielding effect series of shielding effect is S,P,D,F F has worst shielding effect means it cannot shield outer electron from nucleus now if we cannot fill outer electron so outer electron will be more attracted towards nucleus check for writing fast sometimes it happens drive fast and zoom So outer electrons will be more attracted towards nucleus. Why this happens? Because F's shielding effect is bad. This is F and this is outer electron. F is not shielding them. F has poor shielding effect. Its shape is so bad that it is not pulling the nucleus out. If nucleus will pull then atomic radius will decrease. Here decrease is very high because F's shielding effect is very poor. Earlier it was D. The story that was going on in 3D and 4D was about D, so D was still shielding, but it was not able to shield at all. Atomic radius is decreasing very much as the size of the atom increases from here to here, very fast, because of poor shielding effect of F-sub-shell. Is it clear? Atomic radius decreases a lot between 58 and 71. That is why the atomic radius of 72 is almost equal to the limit above it. Is it clear? Did you understand it well? If you didn't, then do repeat it. Lanthenoid contraction. What do we call this process? We call this process Lanthenoid contraction. Someone may ask why is it called Lanthenoid contraction? Now the question is, why is it called Lanthenoid contraction? You can say because of Cougar's Shredding Effect of F-Sub-Shell. It's okay. This is also called as screening effect. Screening effect. You screened it. You added it like a screen. You added this inner electron like a screen. Say it is due to poor screening effect. Whatever you say. It doesn't mean anything. So, I think you have now understood the whole exception of atomic radius. I have told you many special things in this. Like, you all are asking that why the atomic radius has decreased suddenly in lanthroids. Although, in the period, the atomic radius should decrease while moving from here to here. But, why the atomic radius has decreased a lot in lanthroids? you can tell because of poor screening effect or poor shielding effect of F sub shield so what I have taught you from this Scandium, Uterium, Lanthanum, Titanium, Vanadium, sorry Titanium T, Zara, Half, Vanadium, that was Nawab Atomic number 57, 72, 73, that is 21, 22, 23 so what I have taught you that when it comes from here, regular trend followed Scandium small then then uterium and then lanthanum. But the trend did not follow from here. Titanium was smaller and Zirconium and Hafnium were almost equal. So why did this happen? Because from 58 to 71 atomic radius was decreased very rapidly. And by decreasing the atomic radius became so small that instead of increasing from here it became almost equal. And why did this happen? Because of poor shielding effect of F subshell. So, this was a long story. Some people teach this in class 12th D block. I have just told you. Very good. This exception is clear. So, these were all the exceptions, kids, which are asked a lot in exams. Right? Let's go. So, after talking so much, we will move on to the next very important topic. That is, ionic radius. Whose radius will we talk about? Ionic radius. Radius of ion So what is the radius of ion? Suppose we have an atom and we have taken out an electron from it so we will have m plus suppose we have an atom and I write m and you have taken out an electron from m so you have m plus or you can add an electron from m and you can add an electron from m and you can add an electron from m Take the electron So these two things can happen What do we call M plus? Ketion What do we call M minus? Anion So the order is that the size of anion is the largest then comes atom then comes ketion ketion is the smallest then atom then anion So why will it happen? The question comes in mind Why such a thing is happening over here? Why cation has the smallest size while anion has the largest size? Why? Why? Why? Why? Let's understand this. Look kids, suppose an electron comes out. This was an atom. One of these electrons came out. So, the effect of the nucleus will increase on the remaining electrons. Isn't it? Right? Suppose you have two brothers and sisters at home. Okay? So, you do satanic acts and your brother also does it. Both of them get beaten equally. Okay? Suppose one of your brothers has gone. Now, your Pitta will be alone. It went away at once. So, one electron went out. So, the effect of the remaining electron increases. By increasing the effect, the atomic radius of the cation decreases. That is why the atomic radius of the cation is smaller than that of the atom. In the atom, the number of electrons was more. In the neutral atom, one electron went out. The nucleus pulled the remaining electron more rapidly. So, the size of the cation is smaller than that of the neutral atom. Let's talk about anion. Hey, hey, hey, hey, Now, you have a brother who lives in Delhi, Delhi, okay? Now, two people are beating your father at home. One more brother has come, so you are happy, right? That something has been beaten and he will get it. So, the same thing, a new electron has come. The effect of the nucleus on all the electrons will be reduced by the new electron. Till now, it was pulling the 4, now it has to pull the 5. By the decrease in the effect, it will expand. Now, the nucleus is not able to pull it so strongly. So, the atomic radius of anion is greater as compared to neutral atom. here one electron is more than the other, so the effect of nucleus is less than the electron so number of electrons is more and atomic size is more here electron is less, so the effect of nucleus is more and atomic size is less so what is the order? anion is bigger than atom why anion is bigger? because there are more electrons in it if electrons are more, then the effect of nucleus is less and the size of cation is less because electron is less, so the effect of nucleus is more so remember one thing the size of cation is smaller than neutral atom and the size of anion is bigger how do we make students imagine this in anion? we say that many electrons have come what has come? many electrons have come many electrons have come and there is a repulsion in electron electron dangerous repulsion in electron electron due to repulsion they expand electron electron has been repulsed so much that it expands remember this negative one is very big The positive one is small. Now what is the question? It is a simple question. H, H plus, H minus. Tell me who is big and who is small. You will say who is the smallest. H plus, then who? H, then who? H minus. I will ask you N minus, N minus 2, N minus 3. Now tell me who is the smallest and who is the biggest. Negative charge is the most on this. Number of electrons is the most. Repulsion is the most. Size is the most. So N minus 3 is the most. Then N minus 2, then N minus. Let's see the next question. I will give you the next question. O2- O-1 So, if O2- has more negative charge, then it will be greater than O-1. Let's see the next question. What else should I give? F plus F minus and F. Tell me, who will be the smallest? F plus. Then who will come? F. F- because the size of electrons increased due to negative charge so this is very simple thing that cation atom anion cation atom anion what happened here? the more negative charge the bigger size like see this one more question very important ok many people must have slept in the lecture how long it is running see this important question chromium 3+, chromium 6+, now tell me which one is big and which one is small so in this 6+, more positive charge more electrons came out if electrons are less and there is more pull on them, then Cr6 plus is small and Cr3 plus is larger you just think that the more positive charge comes, the smaller the size and the more negative charge, the larger the size next question, suppose Fe2 plus, Fe3 plus, tell me which is small and which is larger? Fe2 plus will be larger, Fe3 plus will be smaller, next question is on manganese, Mn2 plus, Mn4 plus, Mn6 plus Who will be the smallest? Who will be the 6 plus? Who will be the 4 plus? And the biggest? Amen? So the positive charge is smaller and the negative charge is larger. So you understood this thing. Let's see the trend of this. Trend, what is your trend? Trend, first along the period. along a period. What will happen along a period? Nothing will happen. If the charge is same along a period, then where will it remain? Nuclear charge is increasing, increasing, increasing, due to which atomic radius will decrease. Second, down a group. What will happen down a group? Nothing will happen. Here also the pattern will remain same. Assume that everyone has the same charge. If the number of shells is increasing while going down, then atomic radius will increase. Means here along a period, atomic radius decrease, along a group, atomic radius increase, which was the regular trend If the regular trend was the same, then it will work. Note that if the charge is same, if the charge is same on all, then it will work. Listen carefully to me, if the charge is same on all, then it will work. Suppose, there is no question, Na+, Mg2+, Al3+. Now tell me, whose is small and whose is big? Tell me, whose is small and whose is big? So now don't think about the normal one, that we are going in period, so the radius of the atom is decreased. concept has changed a bit because it is a paid charge Subway charge is different. Now, the story of charge is same. If charge is same, subway plus 1, subway plus 2, subway plus 3, something like that. Take an example. Li plus, Na plus, K plus. Assume we have this much. Let's arrange this in atomic radius form. It is simple. Rb plus will be the largest, number of shells will be more, then K plus will come, then Na plus will come, then... There is nothing to think about it. Clear? Okay. Question is good, note that when it comes to Isoelectric species or Iso-Electronic species very important Iso-Electronic species which has same number of electrons What are they? What are they? Tell me Same number of electrons like we have question Thank you. We have a question here. O2-N3-F-Na+, Mg2+. We were told to arrange these in atomic radius or ionic radius. Here, it is ionic radius. Arrange in ionic radius. In which? In ionic radius. Now tell me. Everything is different. First thing, these have come from the second period. These have come from the third period. This is the second period and that is the third period. So, I don't understand anything. Oxygen has 8 electrons, 2 minus means 2 electrons are coming, how many are there? 10. Nitrogen has 7 electrons, 3 minus means 3 more electrons are coming, 10. Fluorine has 9 electrons, 1 minus means 1 more is coming, 10. Sodium has 11 electrons, 1 is gone, plus means 1 is gone, 10 electrons. Magnesium has 12 electrons, 1 minus means 1 more is coming, 10. If there are more electrons, 2 plus means 2 is gone, so 10 electrons. So 10, 10, 10, 10, 10 electrons. This species is called Isoelectric, Electronic species. Those species which have same number of electrons are called Isoelectron. Here see all the electrons are same. Charge on Sodium is plus 1, Atomic number of Sodium is 11. 11 electrons were plus 1, 1 electron is 10. 10, 10, 10. So guys, the rule of Isoelectric species is that size is inversely proportional to atomic number. Size is inversely proportional to atomic number. Whose atomic number is big, whose size is small. Size is inversely... Now don't look at group in this. Don't look at period in this. Don't look at group in this. Don't look at period in this. Look at isoelectronic in this. Whose atomic number is big, whose size is small. Let's talk about atomic number. Z's atomic number. 8 U 7 U 9 U 11 and this is 12 the size of the atomic number is the smallest who is the smallest? magnesium then who will come? sodium then who will come? after 11 9 fluorine then who will come? oxygen O2- then who will come? nitrogen N3- are you clear? how did I decide the atomic number? atomic number 12 11 9 8 7 If the number of electrons is same, then the atomic number will be the largest and the size will be the smallest. Atomic number means the charge of nuclear. The one whose charge will be the largest in nuclear will attract the electrons. This is called Iso-Electronic Species. You can easily get the questions from NEET and JEMANES. If it is an easy question, then you will get the questions from NEET and JEMANES. Iso-Electronic is the most asked. For example, I am forming a question and you tell me. up S2 minus P3 minus CL. minus Al3+. We were told to arrange it we were told to arrange it let's remove Al3+. in order of ionic radius. Sulfur's atomic number is 16 2 minus 2 electrons is 18 Phosphorus's number is 15, 3 electrons are 18 Chlorine's number is 17 minus means another one is 18 So, first thing is Isoelectric. In Isoelectric, size is inversely proportional to atomic number. Let's see atomic number. atomic number Z, check it, 16, 15, 17 the atomic number of the largest size is the smallest, the smallest is chlorine after that, sulfur, after that, phosphorus is this clear?

repeat your trend after regular intervals increase after regular interval decrease in a pattern they are called periodic property so the first periodic property we are going to see is given in your book and is very famous for you and that is atomic radius so the conventional definition of atomic radius is that suppose here is a nucleus and here are the shells so the distance of the electron of outermost shell the distance of Electron from the nucleus. Which electron? The electron of the outer shell. Its distance from the nucleus. This is called atomic radius.

But this definition is correct for 9th and 10th class. But if you have come to higher class, then this definition will be wrong. Because you have read the atomic structure chapter that electron is a wave. Electron is not a particle, electron is a wave.

If electron is a wave, then electron will be moving like this. We don't know the exactly defined path of electron. We are not sure about the exact path of electron. Since electron is a wave, the boundary of atom is not defined.

So this definition will be wrong. Which definition? Write it down if you want.

Which definition? That the distance of the electron in the outer most shell from the nucleus of the atom is called atomic radius. This definition will not be valid because of this point that the boundary of atom is not defined because electron is a wave.

So, because of all these problems, we started measuring atomic radius in a new way. How? We measured atomic radius in bonded state or in interaction state. We have stopped measuring in free state, we will not measure individual atoms in bonded state. So, the methods of measurement in bonded state there are many methods which you have to read, which are in your syllabus.

First one is covalent radius, that when covalent bond is formed, then what will be the radius? Now, it is fixed after the bond is formed. Second one is, we have, guys, the Wander-Wall radius.

The third one which we will read is is metallic radius. And the last one we have to study is ionic radius. First, we will understand what are these radiuses and at the end we will also study what is their trend?

How they vary? Which variation? Along the period and down the group variation. So, first we will understand them.

The definition of atomic radius is not valid. Now, we have to understand this type of atomic radius. which is in bonded state and not in free state so that in bonded state, the boundary of atom will be defined covalent radius, Wonderwall radius, metallic radius and ionic radius so let's start with covalent radius a very good morning, a very good afternoon, a very good evening and a very good night whenever you are watching my video I am Alak Pandey, my channel is physics keep on reading, enjoy, it is fun it is morning time, time is 11, I think and today is 17th June and we are going to study periodic table lecture no.4 so let's see what is a covalent radius covalent radius, you had the idea of atomic radius covalent radius, you understand covalent bond suppose there is an atom A and there is an atom A and they are covalent bonds so how do covalent bonds are formed?

by sharing of electrons you must have seen how electrons are formed by sharing of electrons, one electron cloud is shared with another electron cloud In this condition, distance of the previous nucleus to the second nucleus is called distance AA If you halve this distance, that is called covalent radius So what is the method of removing covalent radius of an atom? Take one more atom like that, form its covalent bond with it After making that covalent bond, the distance between the two atoms in the center to center half of that is covalent radius. Clear?

Very easy. Very clear. Now you have understood that two similar atoms form a covalent bond between them after forming a bond, the distance between them there is a name for this distance distance AA you will read the bond length what will you read? bond length so, the half of this bond length is called covalent radius now, what is the good question in this? the good question is that suppose atoms are not similar atoms are different here, what will happen to this distance and this radius?

same because atoms are same Assume atoms are different. Atoms are different. Is covalent bond formed in different atoms?

Yes, it is formed in different atoms. Have you seen the example of HCl? Covalent bond can be formed in different atoms as well. Similar to H2, hydrogen and hydrogen. This is the example of H2.

Now what to do in different atoms? There are two conditions in different atoms. If electronegativity is same. Electronegativity is same.

How will you understand this? Understand this as the power of attracting electrons. If they are same, means the behavior towards electron is same One is saying we need less electron, so the other is saying we need less electron One is saying we need more electron, so the other is saying we need more electron Means the behavior towards electron is same, that is Electronegativity So suppose Electronegativity is same for both And there are two different atoms, one is A and one is B And between them, this covalent bond is formed Now, the distance A-B which we can call as Bond length that is equal to radius of A plus radius of B but note here that A and B radius can be equal or not but here definitely both have same radius so here I will give you a simple question that is the Bond length in HCL is same or not HCL or any other where electronegativity is same like in methane, CH4 Here, the electronegativity of carbon and hydrogen is same.

The electronegativity of carbon and hydrogen is same. They are of the same nature. So, we will be asked, is its bond length this much?

If the radius of carbon is this much, then we will be asked, is the radius of hydrogen this much? Then you will get the problem out. The second condition is, if electronegativity is different.

If electronegativity is not the same, then what to do? Electronegativity is different means, one has more electronegativity and one has less. The more electron, the more the electron will attract.

The electron clouds will enter the system. Let's assume that the electronegativity of A is the same as that of B. If A is the same, then the system will be like this. B, A. The electron clouds will shift towards A.

The bond length, which we call the distance between A and B, this distance between A and B will be equal to RA plus RB minus 0.9 multiplied by psi A minus psi B. note the formula, I have written it in a notebook let's move from here. what is written? distance between A and B let's write the formula of electronegative difference here.

distance between A and B ball length is equals to RA plus RB minus 0.9 chi A minus chi B. Now why did we get this term minus? It is a matter of thinking.

It would have happened that the electron cloud would have come inside. That means the radius would have been reduced a little. The electron cloud would have come inside. For this, we have put minus here.

Now what is the need here? The need is the electronegativity of A and B. So if electronegativity is different in different atoms, then the minus symbol has to come.

If it is the same, then simple, we have to get RA plus RB. Now the question can be asked, what is the radius of hydrogen? The answer is the bond length of HCl.

The bond length of HCl will be given, the radius of hydrogen will be given, the electronegativity of both will be given, and the radius of chlorine will be asked. For example, if we take the case of HCl, then the electronegativity of both of them is different. So, the electronegativity of both of them will be given, and the difference of electronegativity will be given. The radius of one will be given, and by adding any variables, it will make one variable disappear.

So, for that you should know this equation. So, this was Covalent Radius. Covalent Radius is one half of the distance between the centers of two combining atoms. If the atoms are same, if they are different, then the distance between A and B is RA plus RB.

And if the electronegativity is also different, then you can use this formula to find the covalent radius of both the atoms. So, this was our covalent radius. Now we have to study the second type of radius Second type is Wonderwall radius What is Wonderwall radius? Covalent bond is known to be shared by electron Wonderwall force is in neutral molecules Not in bond molecules Wonderwall force is in any bond You are learning since childhood that the molecules have intermolecular forces of attraction The molecules, the molecules, suppose there is a molecule here Not an atom, a molecule, AB, here also there is a molecule, AB This is a molecule These molecules attract each other You are learning since childhood the intermolecular force of attraction That intermolecular force of attraction is the Wonderwall force That intermolecular force of attraction, which we learn since childhood, what is its name? Wonderwall force So,Wonderwall force When will the bond of the boundary wall be formed?

Without any bond, sorry, boundary wall radius When will it be formed? When will we talk about boundary wall radius? When there is no bond Suppose, here is one molecule of hydrogen Here is another molecule of hydrogen Now there is no bond between them Only intermolecular force of attraction is there between them At this time, the distance of their center to center Distance between hydrogen and hydrogen molecule Divided by 2 is known as Wonder wall radius So where to apply wonder wall radius?

In atom or molecule? In molecule Two molecules which were as close as possible came in front What did I say? Two molecules which were as close as possible came in front in closest approach Can't come close with this If you bring close with this they will run away If you bring close with this they will be far away Nucleus will have repulsion in nucleus Electron will have repulsion in electron As close as possible came in front at that time, half of the distance from center to center is Wonder Wall Radius so now it will count without any bond count is Wonder Wall Radius clear?

let's see another example and explain suppose this is a molecule A,B let's make one more here A,B someone told us that we need Wonder Wall Radius of B Wonder wall radius of B. So, we have brought the close from both the molecules. Now, see the distance between B and B.

The distance between B and B in the closest approach. Divide by 2, that is, Wonder wall radius of B. Nobody told us that we need the Wonder wall radius of A. So, the distance between A and A, measure the distance between them. Distance between A and A, divide by half.

Wonder wall radius of A. Clear? Wonder wall radius is found in molecules.

In molecules, different atoms are found. So, the approach I am telling you is like this. When B is found, B is placed in front of B.

When A is found, A is placed in front of A. Take distance from closest approach and divide by half. It will be very clear.

The biggest use of these is in inert gases. Ok, tell me what are the inert gases? What are the noble gases?

Do they make bonds? No, they don't. Right? In most of the cases, noble gases are bonds.

That's why they are inert, they don't react with anyone. So, the radius of noble gases is the bond-revolved radius. They won't react, they won't make bonds. So, without bonds, as much as they can get close to us, for example, I took helium here and helium here. As much as they can get close, I took the distance of their center to center, distance of helium to helium, Divide by 2, that is radius of helium.

And which is this radius? Wonder wall radius. Someone may ask you, what is the radius of helium? Listen to my question carefully.

What is the radius of helium covalent? We cannot find it. Because it will not form a bond. It will not form a bond. What is the radius of helium?

Wonder wall radius. So, wonder wall radius is very very important for inert gases and noble gases. So, this was the second type of radius.

Now, I am going to ask you a question. Which radius will be bigger? Wonder wall radius or covalent? Think before you reply.

Which radius will be bigger? Wonder wall radius or covalent radius? Think before you reply. See, in Wonder wall radius, you can see that there is a gap in the middle.

So, this radius will definitely be bigger. What happened in covalent radius? Overlapping.

In covalent radius, the overlapping radius will be less and this radius will be more. So, Wonder wall radius is always greater than covalent radius. We will put this in the notes.

very very important, I will teach you in exception also in one place there will be exception and there you will get its explanation you will get example that wonderwall radius is always greater than covalent radius covalent is overlapping in wonderwall atoms are 2 then definitely this radius will be bigger I think you understood what is the border wall radius and where it is used the lecture which will make notes in my lectures will be more beneficial I give very lengthy lectures in very short time if you go to take this lecture in Kota Vata Coaching then you get at least 10-12 lectures I condense those lectures in 7-8 if any of my student is studying in Kota or if any of my student is watching my video then you tell me where is the shortfall topic is left out. So, you can read from any teacher. The topic is the same but I have to condense it. Because we are on an online platform, we cannot afford 2-2 hours of videos. So, it is important that you make notes.

I am telling you those things quickly. I am not leaving out any talks. Let's move ahead.

Today, you will see my exceptions. Then, you will see my exceptions from the previous table. Then, you will understand.

Anyways, let's move ahead. Now, we will talk about the third type of radius. That is, Metallic Radius.

Brother, Metallic Radius As the name suggests, it should be metal, then also it will be metallic radius Metal does not make covalent bonds, ionic bonds, coordinate bonds Metal has a different type of interaction For example, if I tell you that you have an iron rod What is there in that? Iron, iron, iron, iron, iron, iron, iron, iron How? 1D, 2D or 3D? Tell me, 1D, 2D or 3D? 1D, 2D or 3D?

In 3D, right? Iron rod is 3 dimensional, iron is everywhere Covalent bond cannot be made, for covalent bond we need one metal and one non metal Ionic bond also cannot be made, in that metal and non metal Covalent bond has sharing of electron, metal will not share electron Coordinate bond has one donate and one donate, nothing like that will happen So here a new type of bond is made, which we call as metallic bond So how metallic bond is made, you know that metals have free electrons Metals have what? Free electrons, everyone has read it So free electrons of metal keep floating on the surface.

Suppose there is a metal plate here. Suppose I have a metal plate. Now electrons are floating on that plate. Now those electrons will attract the next metal as well.

How will they do it? Suppose this is an atom and this is another atom. Let me explain two atom examples.

This electron is of this side and this is of that side. Here is the nucleus and here is the nucleus. This electron is very free. It is moving here and there.

So this electron has also held this nucleus and this nucleus and also held this nucleus and this nucleus You can understand that electron is flowing like glue Right? You can understand that electron is spread like glue and all the nucleus are stuck all the free electrons This type of bonding is called as metallic bonding or lattice of metal The structure of metal is like this in which there are close packing structures HCP, CCP, FCC you have to study in 12th class, if someone has studied then he must have seen it so this bonding in which metal electrons attract the nucleus and keep bonds or electrons keep flowing and sticking, that is called metallic bonding at this time, the distance between two atoms in the center to center of metal is divided by 2 that is metallic radius there is no other story to tell about it metallic radius is to make lattice of metal, make crystal of metal metal in crystalline form or amorphous form? crystalline form amorphous is that which does not have any shape or size which can be changed metal is in crystal form or defined shape? so in defined shape, take the distance between two atoms and divide it by 2 that is metallic radius my last question is now tell me, covalent radius wonder wall radius wonder wall radius and metallic radius, which is the largest and which is the smallest, arrange it completely let's do it by ourselves I think the largest is going to be the wonder wall because the metallic was like this, the wonder wall was like this and the covalent was like this this is covalent, this is wonder wall and this is metallic so the largest is going to be the wonder wall, definitely, so the wonder wall radius is the largest after this, do this, think and say this is the smallest, it is overlapping, after this, metallic radius and after metallic, covalent so this is given in books you must have understood how it came the biggest one is underwall because there is no bond after that metal, there is no overlapping after that covalent because overlapping has also happened so guys these were very basic things in which we have explained in different ways Let's talk about different types of radiuses of atoms. Now we will talk about their variations.

We have understood three types of radiuses. Which are covalent, Wonderwall and metallic. The biggest one is Wonderwall, then metallic and then covalent.

Let's talk about variation of atomic radius. How it will vary? You know what are the variations to be studied? One is along period and another is down the group. In group, we study from top to bottom, top to bottom.

In period, we study left to right, left to right, right to left, or right to left. I will tell you next time for sure. Promise. So left to right.

Let's take any one example I always explain with second plate example Let's take second plate example Let's take lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine and neon Atomic number 3, 4, 5, 6, 7, 8, 9, 10 That is atomic number that is Z What is Z called? Atomic number What does Z tell? Number of protons where do protons go? in the nucleus in the nucleus so we call this as nuclear charge what do we call this? nuclear charge what happens in the nucleus?

proton and neutron why is there a charge? because of proton so we call this as nuclear charge why is there a charge? because of proton who is there in the nucleus? proton and neutron there is no charge on neutron there is positive charge on proton suppose there are 3 protons in someone's nucleus So, how much is the total nuclear charge on it?

3 We also call it as nuclear charge Nuclear charge Ok Electronic configuration 2,1 2,2 2,3 2,4 2,5 2,6 2,7 and 2,8 See, all of them have the same number of shells The number of shells are same How many shells are there? 1,2 Here, 1,2 Here, 1,2 Here, 1,2 Here, 1,2 2,2 shells So, there is no difference from the shell Everyone has the number of orbit. So, what will be the difference?

What will be the difference? The difference will be due to nuclear charge. How much will it be due to nuclear charge?

Nuclear charge is due to protons. See here, the outer electron is being pulled by 3 protons. And here, the outer electron is being pulled by 6 protons. and here see this outer electron it is being pulled by 9 protons so brother its size will be small or not?

think and tell me how many protons are being pulled here? 9, so when we pull 9 protons then its size will be smaller here 6 are being pulled and here only 3 protons are there So, because protons increase as they go left to right, number of protons increases. Now, what we will use for number of protons technically? Nuclear charge. So, we will say that because nuclear charge increases, what happens by increasing nuclear charge?

Protons increase due to which electron gets attracted. So, what increases on electron? Attraction increases.

I'm sorry. and this attraction brings the electron near the nucleus due to which atomic radius decreases so the general trend is that atomic radius decreases when it moves left to right atomic radius decreases when it moves left to right what is the reason? increase in nuclear charge then comes down the group top to bottom so there is no special story in this when it goes down, do you know that number of shells increases? everyone knows, take an example Hydrogen, Lithium, Sodium, Potassium, Atomic Number 1, 3, 11, 19 Number of Shell 1, 2, 1, 2 Shells 281, 3 Shells 288, 1, 4 Shells So definitely its size will be big 1, 2, 3, 4 and its size will be small, it is 1 shell You are seeing number of Shells 1 Shell, 2 Shells, 3 Shells 4, K, L, M, N So, the number of shells is increasing and the electron is going away from the nucleus.

So, definitely size increases when it goes down. So, when it goes down, atomic radius increases with me and decreases from left to right. So, this is the world. You must have read this in 9th and 10th.

The question arises with exception. You know that. You also search.

You must have come to see one of my videos that where is the exception. Everyone knew this. Let's talk about the exception.

First understand one thing. Along a period, nuclear charge increases due to which atomic radius decreases. Down the group number of shells increases, in this case atomic radius increases. If any property is decreasing, then it increases in this direction.

If it is decreasing here, then it will increase here. If something is increasing for a longer period, then it will decrease down the group. This is opposite.

Now I will show you the exceptions that you can see in the video. Now the video has started. The concept of ionic radius is going to come from here.

Many people will close the video and go. So, their souls. God bless them because they left it on the main topic. Let's start with the exception story. The first exception is going to be in period no.1.

The first period elements are hydrogen and helium. At left to right, the atomic radius should be decreased. But what happens is that the atomic radius of helium is greater than that of hydrogen. What should have happened is that the atomic radius should have decreased, but the atomic radius of helium is greater than that of hydrogen.

Reason? The reason is very simple. What is the gas of helium? Nobel gas.

What is defined for Nobel gas? Wonderwall radius. End of story, end of game.

End of discussion. What is defined for Nobel gas? Wonderwall. And what is the radius of hydrogen? Covalent.

So, we know that Wonderwall radius is greater than Covalent radius. We can't always take it, but we have to take it in noble gas, they don't have any other radius. Sometimes the question arises, why is the radius of Helium more than Hydrogen? When the radius should be less wherever we go.

So, you can say that only Wonderwall radius is greater than Covalent radius. Same exception will come in period number 2. Period 2, Lithium, Beryllium, Boron, Carbon, Nitrogen, Oxygen, Fluorine, Neon. Should I arrange something for this?

So, when we go this way, atomic radius will decrease. When we go left to right, atomic radius will decrease. So, it will decrease. Less lithium, sorry, more lithium, then beryllium, then boron, carbon, nitrogen, oxygen, fluorine. Fluorine is fine.

Atomic radius is decreasing this way. But, the radius of neon is more than these. Why? The reason is this.

Which radius of neon will be defined? Wonder wall. rest of the Sodium, Magnesium, Aluminium, Silicon, Phosphorus, Sulphur, Chlorine and Argon will come first because it being a noble gas only it has Wonderwall radius. it does not have covalent radius.

Is that clear? So this was the first exception of Wonderwall radius that all the noble gases have atomic radius exceptionally high. Is it clear?

Now let us show you an amazing exception of D block. So you must have read D block in periodic table. Where does D block start? Atomic number 21, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc.

Okay? 22, 23, 24, 25, 26, 27, 28, 29, 30. So, what are you thinking? How will the atomic radius be? The expectation is that by going this way, Nuclear charge is increasing, 23, 24, 25 number of protons are increasing due to which atomic radius should decrease we were thinking like this, what were our expectations so nowadays you do that, what is that thing called?

expectations versus reality so let's see reality, reality is little different what happens in reality? there is little difference in reality from here to here atomic radius decreases then from here to here atomic radius decreases becomes constant and then from here to here atomic radius increases when you read exception case then only selection will happen so in the beginning atomic radius decreases then in certain period it becomes constant then after that it increases, it doesn't decrease regularly, in reality it happens now why is this happening? this question also comes come children let's do its configuration scandium 21, if you do the configuration of 21 then 1 is 2, 2 is 2, 3 is 2 I will show you quickly, 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d1, this is it 2, 2, 4, 6, 10, 2, 12, 6, 18, 20, 21, 3d1, very good so kids, its configuration will come, of this KDM, 3d1, 3d2, 3d3 what comes in place of 3d4 of chromium, 3d5, exceptional configuration also of manganese D5 is also there, Iron is D6, Cobalt is D7, Nickel is D8, D9, D10 You know D9 is not available, D10 is available, Copper is also exceptional I have told you many times that two exceptions are in Chromium and Copper Half field is more stable and full field is more stable So, one question can also be asked that in the first D series 3D1, 3D2, 3D3, 3D4 so you can say 3D series, this is called 3D series there is no configuration in 3D series so you will say there is no D4, D9 here the question is something else that why this pattern is there see from here to here, what is happening? electrons are filling up, 1, how many came in this?

2 how many came in this? 3 it is increasing here an exceptional thing happened in d5, d5 and d6, let me show you I have taken 5, d is 5 1, 2, 3, 4, 5 and this is 6 now what is happening when 5 and 6 come by getting an extra electron here starts the repulsion of electrons as the number of electrons increases listen to me carefully as the number of electrons increases the repulsion of electrons starts Now if we repel electrons, then the size of the atom will increase. Like from here to here, electrons were less. So electron repulsion is less.

But what is increasing from here? Nuclear charge. 21, 22, 23, the nuclear charge is increasing. Or you can say that Z is increasing. So from here to here, because of Z increasing, the atomic radius is decreasing.

because electron repulsion is not that much what happened here? electron repulsion is there due to which it is trying to spread and nuclear charge is increasing due to which atomic radius is trying to decrease electron repulsion is there due to which atomic radius is trying to increase nuclear charge is increasing and by increasing nuclear charge and positive charge radius is trying to decrease here both the factors are fighting each other so here Z is increasing who is balancing it? electron by electron both the factors are equal to each other so neither the atomic radius can increase nor decrease what happened here is that Z is increasing a lot so much that the repulsion of electrons is not that much there are very few electrons and not much repulsion there is only one factor which is the increase of nuclear charge here electrons are increasing and repulsion is so much that it is fighting with this factor and atomic radius is not increasing nor decreasing now come forward D8, D9 Let me make D8.

1, 2, 3, 4, 5, 6, 7, 8. Now see, the repulsion of electrons is very high. Here the repulsion factor of electrons is more than the repulsion factor of nuclear charge. Here the repulsion of electrons is so high that the radius of the atom is increasing. Nuclear charge is also increasing due to which the radius of the atom should decrease. But that factor is not dominating much.

as compared to electron-electron repulsion so this was the story here that in the beginning only the nuclear charge was increasing later the electron repulsion was increasing the nuclear charge was also equal neither the atomic radius could increase nor decrease in the end, the repulsion of electron-electron was the highest because the number of electrons was increasing as the number of electrons increases the number of electrons will increase as and when electron-electron repulsion will increase ok And we saw that the repulsion of electrons and electrons was so much that they expanded. So, we said that in the beginning we dominated this factor and then this factor and in between both. So, in the exam, the question arises that which one is the biggest and which one is the smallest. Suppose, we ask them to arrange and one of them gives us four elements.

Any four elements, like here you are saying almost equal, it is said that compare Magnesium, Cobalt, Titanium, and Bidonium. What is happening in the beginning? It is decreasing, then it is increasing.

So, there can be a confusion that the radius of zinc is increased or the radius of titanium is increased. Here it is decreasing, then it is increased, in between it is decreased and increased. So, to end all these confusions, we give you a trick so that you can remember it completely. Scandium, Titanium.

Zinc, Validium, Cobalt, Nickel Remember, in Scooty, there is no Zinc Scooty, Scandium, Titanium I don't care about zinc, same with vanadium, no one in the last, this is our order, bigger, and then cobalt will come out because the order was very disturbed here so we made it like this zinc in scoopy same no one and what to write to the rest of the kids equal so note this you should remember this exception in 3D series and this order is also in 4D and 5D series 4D means the series below it 5D means the series below it this is the exception in that too there is no need to remember the order it is not being asked let's show you the next exception exception number 3 this is also inside D block very important let's understand let's assume that we have scandium yamaha lau egg, remember? this is 3D series this is 4D series this is 5D series atomic number 21 atomic number 57 next, next to this scandium, titanium, atomic number 22 T, Zara half titanium, zirconium, hafnium I have taught you all these in the video number 2 of the Pivot Table how to remember it, t is half here atomic number is 72, pay attention some elements have disappeared from here which you know that 58 to 71 where they have gone? in lanthenoids where they have gone?

in lanthenoids after this next, vanadium that was new Meridiem, Noabium, Tantella Here 73, here 23 and so on Children, you are going to the downer group, so what will you expect while going to the downer group? What will you expect while going to the downer group? You will expect that the radius of the atom will increase As we asked here what will you say about the radius of the atom? You will say that the radius of the atom will be smaller than the radius of the scandium, and the radius of the uterine will be larger than that of the lanthanum You will say this only As you go down, the number of shells increases and the atomic radius increases Absolutely correct Here the trend has changed.

Here the trend was titanium, bigger than that zirconium, and haplium is equal to that. It has grown from here to here, but here and here it is almost equal. Like here the same thing happened, small of meridium, new of sodium, and almost equal to tantalum. What is happening here? This 4D and 5D 4D and 5D series atomic radius is almost same.

Here it didn't happen, but it started with the next element. So, you must be thinking that some story must have happened here. Some story started after 57. This is a regular trend.

This is following a normal trend. Here some abnormality happened, their radius doesn't match. So, something must have happened here. Let's understand what is special about lanthanoids. After 57, the jump happened.

After that, the atomic radius was almost equal. From here, the atomic radius should have increased. It didn't. so in lanthinoids In lanthenoids, that is account number 58 to 71, you know that slowly slowly slowly slowly F-sub-shell fills up.

4F fills up here. When 4F fills up, there is a very big contraction which we call lanthenoid contraction. What happens? What happens? Say with me, lanthenoid contraction.

means when we move in 4F, then the size becomes very less suddenly the size becomes very less when we move in lanthanoid series, then the size of atoms in lanthanoid series becomes very less I am showing you the lanthanoid series when we move from here to here when we move from 58 to 70 in lanthanoid series, the size of atoms decreases very fast it decreases so fast that even when 72 number comes, the size of atoms remains small due to which the radius of zirconium and haemium is not equal If the number of shells would have increased, then the radius should have been higher. But due to this lanthanoid contraction, a very massive contraction, in lanthanoid, as soon as they run, 58, 71, the size of the atom becomes very small. And due to this contraction, the size of the haplium becomes small.

And due to which the radius of zirconium haplium is almost equal. Or due to which the radius of 4D and 5D series, someone asks you why the radius of 4D and 5D series is equal. Why not, the radius increased from here to here, then you will say due to lanthanoid contraction.

We all know what is lanthanoid contraction. So, we will have to explain. First, note that when 4D to 5D is applied, if you leave this, its idiom, uterine and latinum, after this, the radius of this and this is equal to this, and this and this is equal to this, and this and this is equal to this. Why did this happen?

Because the radius had to be increased from here to here. But after lanthanum, the radius was suddenly very small, 58 to 71. And when it came to 72, the radius was small, due to which these two are almost equal. Now, what is the reason for this? So, look for the reason. Reason for kids to go to the head in a new topic in the table I will teach you all should read We call it shielding effect This is a new topic, let's add heading Shielding effect What is shielding effect?

Suppose this is a multi electron system Here is This electron will repel this electron and the nucleus will attract this electron. So we can say that this electron is trying to protect the outer electron from the nucleus. These electrons have hidden the nucleus inside and are protecting the outer electron like a shield.

These are inner electrons. So what do the inner electrons do? They shield. Who? outer electrons from which we shield?

from nucleus, we save from nucleus we reduce the effect of nucleus this is called shielding effect where will this happen? in multi electron system who shows? inner electron this is like shield we hide the nucleus inside and don't let the effect go out to the outer electron we will understand this only then we will understand lanthanol contraction ok we have 4 subshields, S, P, D, F The most shielding effect is with S, then P, then D, then F.

You will ask why? Due to their shape. S is closest to the nucleus. So, S is closest to the nucleus and keeps it pressed. F is very dispersed.

How is the shape of F? Very dispersed. It is 8-fold, completely scattered.

If it is completely scattered, then the nucleus, suppose F is like this. This is F. Now, what will this save the external electron? And what is S?

This is S. It has closed the nucleus in itself. So it can save the external electron.

So the shielding effect of S is mostly of P, D and F due to their shapes. S completely presses the nucleus in itself, saves the external electron. F cannot save it.

So this is called shielding effect. So we have understood the shielding effect in the multi electron system. Inner electrons shield the outer electrons. Who are they shielding?

from where? from nucleus we save from the effect of nucleus, how we save? we repel it and if we want to imagine it, we make it like a shield the biggest shield is of S, P, D and F after understanding all this, you come back why this contraction happened? why this contraction happened from 58 to 71? so the filling here 4F0, 4F1, 4F2 and 4F is the filling upto 14 there is some disturbance in between but overall trend will be same F has poor shielding effect now you saw who is the last in shielding effect series of shielding effect is S,P,D,F F has worst shielding effect means it cannot shield outer electron from nucleus now if we cannot fill outer electron so outer electron will be more attracted towards nucleus check for writing fast sometimes it happens drive fast and zoom So outer electrons will be more attracted towards nucleus.

Why this happens? Because F's shielding effect is bad. This is F and this is outer electron.

F is not shielding them. F has poor shielding effect. Its shape is so bad that it is not pulling the nucleus out.

If nucleus will pull then atomic radius will decrease. Here decrease is very high because F's shielding effect is very poor. Earlier it was D. The story that was going on in 3D and 4D was about D, so D was still shielding, but it was not able to shield at all. Atomic radius is decreasing very much as the size of the atom increases from here to here, very fast, because of poor shielding effect of F-sub-shell.

Is it clear? Atomic radius decreases a lot between 58 and 71. That is why the atomic radius of 72 is almost equal to the limit above it. Is it clear?

Did you understand it well? If you didn't, then do repeat it. Lanthenoid contraction. What do we call this process? We call this process Lanthenoid contraction.

Someone may ask why is it called Lanthenoid contraction? Now the question is, why is it called Lanthenoid contraction? You can say because of Cougar's Shredding Effect of F-Sub-Shell. It's okay. This is also called as screening effect.

Screening effect. You screened it. You added it like a screen.

You added this inner electron like a screen. Say it is due to poor screening effect. Whatever you say.

It doesn't mean anything. So, I think you have now understood the whole exception of atomic radius. I have told you many special things in this.

Like, you all are asking that why the atomic radius has decreased suddenly in lanthroids. Although, in the period, the atomic radius should decrease while moving from here to here. But, why the atomic radius has decreased a lot in lanthroids?

you can tell because of poor screening effect or poor shielding effect of F sub shield so what I have taught you from this Scandium, Uterium, Lanthanum, Titanium, Vanadium, sorry Titanium T, Zara, Half, Vanadium, that was Nawab Atomic number 57, 72, 73, that is 21, 22, 23 so what I have taught you that when it comes from here, regular trend followed Scandium small then then uterium and then lanthanum. But the trend did not follow from here. Titanium was smaller and Zirconium and Hafnium were almost equal.

So why did this happen? Because from 58 to 71 atomic radius was decreased very rapidly. And by decreasing the atomic radius became so small that instead of increasing from here it became almost equal.

And why did this happen? Because of poor shielding effect of F subshell. So, this was a long story.

Some people teach this in class 12th D block. I have just told you. Very good.

This exception is clear. So, these were all the exceptions, kids, which are asked a lot in exams. Right? Let's go. So, after talking so much, we will move on to the next very important topic.

That is, ionic radius. Whose radius will we talk about? Ionic radius. Radius of ion So what is the radius of ion?

Suppose we have an atom and we have taken out an electron from it so we will have m plus suppose we have an atom and I write m and you have taken out an electron from m so you have m plus or you can add an electron from m and you can add an electron from m and you can add an electron from m Take the electron So these two things can happen What do we call M plus? Ketion What do we call M minus? Anion So the order is that the size of anion is the largest then comes atom then comes ketion ketion is the smallest then atom then anion So why will it happen?

The question comes in mind Why such a thing is happening over here? Why cation has the smallest size while anion has the largest size? Why?

Why? Why? Why? Let's understand this.

Look kids, suppose an electron comes out. This was an atom. One of these electrons came out. So, the effect of the nucleus will increase on the remaining electrons. Isn't it?

Right? Suppose you have two brothers and sisters at home. Okay?

So, you do satanic acts and your brother also does it. Both of them get beaten equally. Okay?

Suppose one of your brothers has gone. Now, your Pitta will be alone. It went away at once.

So, one electron went out. So, the effect of the remaining electron increases. By increasing the effect, the atomic radius of the cation decreases.

That is why the atomic radius of the cation is smaller than that of the atom. In the atom, the number of electrons was more. In the neutral atom, one electron went out.

The nucleus pulled the remaining electron more rapidly. So, the size of the cation is smaller than that of the neutral atom. Let's talk about anion.

Hey, hey, hey, hey, Now, you have a brother who lives in Delhi, Delhi, okay? Now, two people are beating your father at home. One more brother has come, so you are happy, right? That something has been beaten and he will get it. So, the same thing, a new electron has come.

The effect of the nucleus on all the electrons will be reduced by the new electron. Till now, it was pulling the 4, now it has to pull the 5. By the decrease in the effect, it will expand. Now, the nucleus is not able to pull it so strongly. So, the atomic radius of anion is greater as compared to neutral atom. here one electron is more than the other, so the effect of nucleus is less than the electron so number of electrons is more and atomic size is more here electron is less, so the effect of nucleus is more and atomic size is less so what is the order?

anion is bigger than atom why anion is bigger? because there are more electrons in it if electrons are more, then the effect of nucleus is less and the size of cation is less because electron is less, so the effect of nucleus is more so remember one thing the size of cation is smaller than neutral atom and the size of anion is bigger how do we make students imagine this in anion? we say that many electrons have come what has come?

many electrons have come many electrons have come and there is a repulsion in electron electron dangerous repulsion in electron electron due to repulsion they expand electron electron has been repulsed so much that it expands remember this negative one is very big The positive one is small. Now what is the question? It is a simple question.

H, H plus, H minus. Tell me who is big and who is small. You will say who is the smallest.

H plus, then who? H, then who? H minus. I will ask you N minus, N minus 2, N minus 3. Now tell me who is the smallest and who is the biggest. Negative charge is the most on this.

Number of electrons is the most. Repulsion is the most. Size is the most.

So N minus 3 is the most. Then N minus 2, then N minus. Let's see the next question. I will give you the next question. O2- O-1 So, if O2- has more negative charge, then it will be greater than O-1.

Let's see the next question. What else should I give? F plus F minus and F. Tell me, who will be the smallest? F plus.

Then who will come? F. F- because the size of electrons increased due to negative charge so this is very simple thing that cation atom anion cation atom anion what happened here? the more negative charge the bigger size like see this one more question very important ok many people must have slept in the lecture how long it is running see this important question chromium 3+, chromium 6+, now tell me which one is big and which one is small so in this 6+, more positive charge more electrons came out if electrons are less and there is more pull on them, then Cr6 plus is small and Cr3 plus is larger you just think that the more positive charge comes, the smaller the size and the more negative charge, the larger the size next question, suppose Fe2 plus, Fe3 plus, tell me which is small and which is larger? Fe2 plus will be larger, Fe3 plus will be smaller, next question is on manganese, Mn2 plus, Mn4 plus, Mn6 plus Who will be the smallest?

Who will be the 6 plus? Who will be the 4 plus? And the biggest?

Amen? So the positive charge is smaller and the negative charge is larger. So you understood this thing. Let's see the trend of this.

Trend, what is your trend? Trend, first along the period. along a period. What will happen along a period? Nothing will happen.

If the charge is same along a period, then where will it remain? Nuclear charge is increasing, increasing, increasing, due to which atomic radius will decrease. Second, down a group. What will happen down a group?

Nothing will happen. Here also the pattern will remain same. Assume that everyone has the same charge.

If the number of shells is increasing while going down, then atomic radius will increase. Means here along a period, atomic radius decrease, along a group, atomic radius increase, which was the regular trend If the regular trend was the same, then it will work. Note that if the charge is same, if the charge is same on all, then it will work. Listen carefully to me, if the charge is same on all, then it will work.

Suppose, there is no question, Na+, Mg2+, Al3+. Now tell me, whose is small and whose is big? Tell me, whose is small and whose is big?

So now don't think about the normal one, that we are going in period, so the radius of the atom is decreased. concept has changed a bit because it is a paid charge Subway charge is different. Now, the story of charge is same.

If charge is same, subway plus 1, subway plus 2, subway plus 3, something like that. Take an example. Li plus, Na plus, K plus. Assume we have this much. Let's arrange this in atomic radius form.

It is simple. Rb plus will be the largest, number of shells will be more, then K plus will come, then Na plus will come, then... There is nothing to think about it. Clear?

Okay. Question is good, note that when it comes to Isoelectric species or Iso-Electronic species very important Iso-Electronic species which has same number of electrons What are they? What are they? Tell me Same number of electrons like we have question Thank you. We have a question here.

O2-N3-F-Na+, Mg2+. We were told to arrange these in atomic radius or ionic radius. Here, it is ionic radius. Arrange in ionic radius. In which?

In ionic radius. Now tell me. Everything is different.

First thing, these have come from the second period. These have come from the third period. This is the second period and that is the third period.

So, I don't understand anything. Oxygen has 8 electrons, 2 minus means 2 electrons are coming, how many are there? 10. Nitrogen has 7 electrons, 3 minus means 3 more electrons are coming, 10. Fluorine has 9 electrons, 1 minus means 1 more is coming, 10. Sodium has 11 electrons, 1 is gone, plus means 1 is gone, 10 electrons. Magnesium has 12 electrons, 1 minus means 1 more is coming, 10. If there are more electrons, 2 plus means 2 is gone, so 10 electrons.

So 10, 10, 10, 10, 10 electrons. This species is called Isoelectric, Electronic species. Those species which have same number of electrons are called Isoelectron. Here see all the electrons are same. Charge on Sodium is plus 1, Atomic number of Sodium is 11. 11 electrons were plus 1, 1 electron is 10. 10, 10, 10. So guys, the rule of Isoelectric species is that size is inversely proportional to atomic number.

Size is inversely proportional to atomic number. Whose atomic number is big, whose size is small. Size is inversely... Now don't look at group in this. Don't look at period in this.

Don't look at group in this. Don't look at period in this. Look at isoelectronic in this. Whose atomic number is big, whose size is small. Let's talk about atomic number.

Z's atomic number. 8 U 7 U 9 U 11 and this is 12 the size of the atomic number is the smallest who is the smallest? magnesium then who will come?

sodium then who will come? after 11 9 fluorine then who will come? oxygen O2- then who will come? nitrogen N3- are you clear?

how did I decide the atomic number? atomic number 12 11 9 8 7 If the number of electrons is same, then the atomic number will be the largest and the size will be the smallest. Atomic number means the charge of nuclear. The one whose charge will be the largest in nuclear will attract the electrons.

This is called Iso-Electronic Species. You can easily get the questions from NEET and JEMANES. If it is an easy question, then you will get the questions from NEET and JEMANES.

Iso-Electronic is the most asked. For example, I am forming a question and you tell me. up S2 minus P3 minus CL. minus Al3+. We were told to arrange it we were told to arrange it let's remove Al3+.

in order of ionic radius. Sulfur's atomic number is 16 2 minus 2 electrons is 18 Phosphorus's number is 15, 3 electrons are 18 Chlorine's number is 17 minus means another one is 18 So, first thing is Isoelectric. In Isoelectric, size is inversely proportional to atomic number.

Let's see atomic number. atomic number Z, check it, 16, 15, 17 the atomic number of the largest size is the smallest, the smallest is chlorine after that, sulfur, after that, phosphorus is this clear?

Transcript for:Periodic Properties and Atomic Radius

Transcript for:
Periodic Properties and Atomic Radius