Valence of Elements and Radicals

hi everyone welcome to eagles edgy concepts a platform that provides you with quality education in science and mathematics starting from secondary level all the way up to a level if you are visiting this channel for the first time please subscribe and keep on sharing so that you can help yourself and somebody better themselves in science and mathematics education this video we are looking at igcse chemistry and the topic is valencia by the end of this video you should be able to define valency thereafter you will be able to determine the variance of elements on the periodic table and finally you will be able to determine the valency of radicals without further ado let's go straight into the subject to begin with let's just give a recap of what the periodic table is so by now we know that the periodic table is simply a rectangular arrangement of elements according to their atomic numbers now the priority table as i like to call it is a very important tool for chemistry if you want to pass chemistry there is need for you to understand this important tool called the periodic table now there will be other lessons that will explain in details what the periodic table is all about but because we are looking at balance in this lesson i'm going straight just to mention what a group is because a group is related to the valency of an element so a group is simply a vertical column okay a group is a vertical column of elements on the periodic table so these group numbers are shown actually using the roman numerals okay so as you can see this is roman numeral number one which is representing this vertical column of elements so meaning the entire column here is group one this one is group two then there is this one here this one is just called the transition element soon you'll understand why then we go to group three so meaning everything in here is group three we go to group four we go to group five we go to group six we go to group seven then we have group eight which they write as group or for a reason that you will be able to understand by the end of this video all right then what is valency you're saying valency is simply the number of electrons an element needs to achieve an octet configuration in other words to achieve stability now an octet configuration is a situation where the outermost shell of an element has eight electrons that's what octet means it simply means it has a total number of eight electrons which means it's completely filled up so if it's not eight then that particular element is not stable so how many elements it needs to reach eight uh is actually what we call an octet configuration and consequently we are defining valency as the number of electrons and elements need to achieve an object configuration in other words we are saying valency is the combining power of an element so now we are saying uh here an element can achieve this octet configuration by either losing or gaining that particular electron depending on whichever one it is easier so for uh for if if the number of electrons is less than four then it is easier to lose them but if it is above four then uh it is not easier to lose them but it is easier to add some more anyway other details about that will be shared in some other videos just make sure you follow through all right now let's begin by determining the valence for elements in groups one two three and four so now these groups have been paired together because the rule that governs how to find the values in these respective groups is actually the same what is that rule so before we can even introduce that rule let's just look at these groups so these are the groups that we are talking about uh this is group one right here this is group two this is group three and this is four so you skip this one like i mentioned it's known as transition meters or transition elements now let's look at the rule how do we find the valency in these uh groups so the rule is very simple for groups one two three and four the the the rule is that the group number is equivalent to the valency now what does this mean so if we say for example this is group one so all the elements in here they've got a variance of one that's what it means so all group one elements have got a variance of one all group two elements have got a variance of two all group three elements have got a variance of three and all group four elements have got a variance of what in four okay so you need to take note of this rule determining the values for groups one two three and four just follow the group number so the group number is the valence of that particular element right let's look at determining values for groups five six seven and eight so determining the group number uh the valence for these groups it also has the same rule now that rule will be given in form of the formula before we do that let's just have a recap these are the groups as you can see in roman numerals we have five group six group seven and group eight which is also called group o yeshua you know the reason why it is so the first thing is balance will be given by the formula 8 minus group number so this means if you are finding for group 5 to find the values you are simply going to say variance for a group 5 element is equals to eight minus five and it will give you three then for group six it is going to be eight minus six which will give you two for group seven it's going to be eight minus seven which will give you one and for group eight it would be eight minus eight which will give you zero now as you can see i said you will know the reason why we equate with zero so this one is called group o because of group zero because it doesn't have uh a valence so for these groups you simply subtract the group number from eight hence you've determined the valence so for this one the variance of nitrogen is three phosphorus is three astertime is three this antimony is three this this map here is also three let's look at what we call the transition elements so now we are saying transition elements have got no fixed variances but variable now this means that the same element can have more than one variance for example iron can have a variance of two in some situations it can be three okay so they are called transition elements now transition is the actual uh the actual literal meaning transition to change we are moving from this thing into the other so that is how the valence of this element also rt behaves so it changes from this value to the other value depending on the compound in which that element is uh been reacted or is being found okay now since these have got no uh definite way of determining the balance they have different balances how then do we know the balance so how to know that valence is very simple just look at uh just look at the the way they've given you for example they'll ask you find the valence of ion in ion 2 sulfate so when they put this this number they've put here the roman numerals they put in brackets represents the valence for the yt uh represents the values for the transition metal okay so here they've put two it means that ion has got a variance of two in this other example as you can see they have put three so it means that ion has got a variance of yt three so that is the simple procedure which it follows lastly but not the least we are also going to look at how to determine the values of what we call radicals now a radical is simply a group of atoms which is present in several compounds but is incapable of independence existence so for the valence of radicals there is no formula on how you can find them no laid down rule the only rule i'm going to tell you is you have to memorize these balances of radicals in literature sources by literature sources i mean check your chemistry textbook that has been recommended to you every recommended textbook has a table of radicals which is going to show you the name of the radical the va the formula of the radical and the violence your duty will just be to master them fortunately unfortunately in the exam they won't even give you these things but you just have to master them put them in your head start practicing all right example of radicals that you're going to encounter in most instances is uh these as displayed here so as you can see for example ammonium which has got the formula nh4 and the variance is one you can check all these all these that are in here they've got a valence of one then we go to carbonate c or three the valence is two so all these that are in here they've got a variance of two then we've got the phosphate which is po4 so the valence here is y t three so these you just need to memorize them no need of uh no formula no rule but just memorize is that simple interact with them memorize as many as you can they're going to help you all right guys thank you so much for watching and uh in the next lesson you you'll see where we are going to be applying this concept of the balance so this is a very important concept that's why it is part of the introduction to chemistry if you miss this part you miss the part to do with the periodic table then things are going to be hard for you so the best thing that you have to do is make sure you follow through this video practice through know the balances thereafter we are going to see how we'll be applying balances in a lot of things for example in the next video that will be uploaded we are going to learn how we can apply the valencies in constructing formulas okay then thereafter we also look at how we can use these formulas to construct equations and it will lead us into balancing equations all those are the things that makes chemistry exciting so be on the lookout thank you for watching