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Current time:0:00Total duration:12:34

Video transcript

there are so many awesome things around us and all of these are made up of atoms but have you ever wondered what makes these tiny atoms stick together in this shape well that happens because of different kinds of chemical bonds between these atoms and today we are going to talk about one of them covalent bond basically these are chemical bonds where atoms mutually share electrons to be together now in the video of ionic bond we have seen how atoms can lose electron and gain electron and get oppositely charged and attract each other stick to each other that makes sense right but how can atoms stick together by just sharing of electrons let's find out so let's take a fluorine molecule for example see one molecule of fluorine has two atoms of fluorine and these two atoms are sticking together now let's see how these atoms are sticking together are they losing electron and gaining electron or something else is happening here so for this let's write down the atomic number of flowing which is nine that means a neutral atom of fluorine will have nine electrons going around it and it's electronic configuration will be 2 comma 7 that means there are 7 electrons in its outermost shell now let's draw the outermost electrons over here and here we are only going to draw the outermost electrons because you know in a chemical reaction only the outermost electrons participate only they are lost or gained okay so there is no need to draw the innermost electrons so 7 in the outermost shell so 7 crosses yes I am representing the electrons with crosses here similarly over here 7 crosses now see we know that atoms they want to become more stable more stable like normal gases and noble gases most of the noble gases have eight electrons in their outermost shell so even these two fluorine atoms will want eight electrons in their outermost shell currently they have only seven now which one will lose and which one will gain will that even happen let's see if this fluorine atom loses an electron to this one see this atom will have eight electrons but this one would have lost one it has six so this is not stable right even though this is stable and happy this is not going to be stable so this kind of business is not going to happen between them nobody's going to lose or gain electron in this molecule so how are they sticking together well in this case they are sharing electrons both these atoms are sharing one one electron with each other something like this so what happens in this case is that this electron of this fluorine is not only going around this fluorine atom but after being shared it is going around both the fluorine atoms similarly this electron of this fluorine is not only going around this fluorine atom but now after being shared it is going around both the fluorine atoms so basically these two shared electrons from one from each of the fluorine is not only bound to one of these fluorine atoms but now they are going around both of these fluorine atoms now you might be wondering how does that help see if you just focus on this fluorine let's see it has six electrons bound to just itself and now these two electrons are also going around it so this fluorine atom experiences six plus two electrons around itself meaning eight electrons around itself and that's why it will find itself to be stable and happy now similarly if you focus just on this fluorine now it has six electrons bound to itself and now these two shared electrons they are also going around it so this fluorine atom experiences eight electrons 6 plus 2 8 electrons around itself so this is stable and this will find itself to be happy so this is how by sorry by sharing one one electrons both of these atoms can complete their octet and become stable now let me explain you the sharing part with one more analogy let's say you and I are dog lovers and both of us have 7 dogs each but for some weird reason we both will be extremely happy if we get to play with 8 dogs each now how can that happen so for that we both can share one one dog with each other something like this see now these two shared dogs they are not bound to play with just me or just you but they will be playing with the both of us okay now in this case if you just focus on me then see I have six dogs which will just play with me but these two shared dogs are also available for me right so I experienced that I have eight dogs to play with 6 plus 2 8 dogs to play with so I'm extremely happy now similarly if we just focus on you you have these six talk just to play with you and now these two dogs are shared so that means even you can play with them that means you will also experience 6 plus 2 8 dogs to play with and that's where you will be extremely happy ok now this is how by sharing our dogs we both get to be happy now see if you want to be happy always then we will have to stick together and keep on sharing our dogs right so in this case I can say that you and I have bonded together now something similar is happening even with the fluorine molecule here the fluorine atoms had 7 electron and needed one more to be stable to gain one it had to share one electron with each other ok that's how they became stable now see if they want to be stable forever they will have to keep on sticking to each other and sharing one one electron with each other right so this is how a chemical bond is formed between these two fluorine atoms and now since this chemical bond is being formed because of sharing of electrons we call this a covalent bond see Co refers to sharing and when it refers to valence electrons and here the valence electrons are being shared right that's why it's called covalent bond ok one last thing C to represent a covalent bond simply without these crosses and circles we can draw a dash between the two sharing atoms just like this one single dash refers to a pair of electrons or two electrons being shared between these two so these two electrons can be replaced by a single Dash and this means that these two atoms have a covalent bond a single covalent bond between them now let's look at a couple of more examples to understand this concept little better this time let's talk about oxygen oxygen has eight electrons going around it and if I write its electronic configuration it will be 2 comma 6 that means there are 6 electrons in the outermost shell let me draw it I'll show it to you so this is the oxygen atom and here there are 6 crosses representing 6 electrons now see it's octet is not complete it does not have eight electrons in its outermost shell that means it is not stable now how can it share electrons with another oxygen atom to have complete update so that both of them have complete octet can you pause the video over here and try to figure this out how many electrons will be shared between these two oxygen atoms now if you have thought about it let's see so if you thought that they will be sharing one electrons let's see what happens if both of them share one of their electrons then see this oxygen atom had six already and now it will have access to one electron from here that means 6 plus 1 7 so that means the octet is still not complete so just sharing one electron is not going to help this time they will have to share two of their electrons with each other something like this let's move this yes so now you can see that this oxygen it had six electrons and now it has access to two more that means its octet is complete there are eight electrons for this oxygen similarly for this oxygen there are 6 plus 2 8 electrons so it's octet is also complete so this time each el the each atom had to share two electrons with each other to complete each of those octet and now both of them are stable so here in this case since there are two pairs of electrons getting shared one this and one this we see that there are two covalent bonds between two oxygen atoms so if you have to write this in simple terms we will say that between two oxygen atoms there are two covalent bonds there is a double covalent bond here whereas in case of fluorine we saw a single covalent bond now let's look at one more example so this time let's talk about nitrogen so nitrogen has seven electrons to in total so it's electronic configuration will be 2 comma 5 that means it has 5 electrons in its outer motion that means its octet is not yet complete now can you pause the video and try to draw it by yourself and show how many electrons will be shared between two nitrogen atoms so that both of them have complete octet pause and try it by yourself first now if you have tried it let's see so here I have one nitrogen atom and I'm showing five electrons in the outermost shell and here I have the second nitrogen atom so see since one nitrogen atom needs three more electrons it has five in the outermost five plus three will be eight so it needs three more electron therefore it needs to share three electrons with the other nitrogen something like this yes now if you see carefully this nitrogen has five plus three eight electrons its octet is complete and similarly this nitrogen's octet is complete and this is how they will covalently exist now over here if we have to count the number of covalent bonds see there is one pair being shared here let me change the color one pair of electron second pair of electron and third pair of electron so in total three pairs of electrons are being shared between two nitrogen's so over here we see that when two nitrogen's share electron there is a triple covalent bond between them okay so we saw that fluorine has single covalent oxygen has a double covalent and nitrogen has triple covalent now one last question how does hydrogen share electron and this question is unique because hydrogen has just one electron and it does not follow the octet rule it does not need to have eight electrons in its outermost shell to be stable but instead it follows do wait rule meaning it needs to have two electrons in its outermost shell to become stable now with this new information can you pause the video and think about how two hydrogen atoms share electrons to be stable now if you have tried it let's see so here I have one hydrogen atom and it has one electron and another hydrogen atom with another electron now we know that hydrogen needs two electrons to become stable so in this case both of these atoms will share one one electron with each other something like this see now this hydrogen atom has one of its own and then one being shared meaning total two electrons so this will be stable it's do it will be complete similarly this hydrogen will have two electrons around it so it's do it will also be complete and this is how they will share electrons by a single covalent bond so here we will write hydrogen has a single covalent bond with another hydrogen and this is how h2 gas exists in nature now let's summarize the video in this video we spoke about covalent bonds basically where atoms share electron to become stable and stick together we saw that these bonds could be single covalent or double covalent or triple covalent bond and the major underlying principle was that if Adam needs one electron then it needs to share one electron if it needs two electron that it needs to share two electrons if it needs three then it needs to share three