Polar Covalent Bonds

by Jason Amores Sumpter
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So now that we've introduced non polar Covalin bonds in our previous lesson videos and this video, we're going to introduced the second type of co violent bond, which is the polar co violent bond. Now, once again, the word koval it here means the sharing of electrons. And so, even in polar co Vaillant Bonds there's going to be sharing of electrons. But the word polar here is really referring to the unequal sharing of electrons between atoms. And so polar Covalin bonds are characterized by unequal sharing of electrons. Now, the reason that the electrons are being shared unequally and polar Covalin bonds is due to different electro negativity is between the atoms. And so what this means is that they're going to pull on the electrons with different amounts of strength. Now, of course, unequal sharing of electrons between atoms is going to lead to an unequal distribution of these negatively charged electrons, and unequal distribution of negatively charged electrons is going to lead to partial charges. And so this symbol right here is the Greek symbol delta, which can be used to symbolize for the word partial, and so you'll see this symbol down below throughout our image. So in our image over here on the left hand side, we're showing you a few examples of polar co Vaillant Bonds. And so the first example that we're showing you is hydrogen chloride whose chemical formula is H C L. So you could see the hydrogen atom over here and the chloride Adam over here Now, hydrogen and chloride have very different electro negativity. Ease chloride polls really, really hard on electrons. It has a high electro negativity, but hydrogen does not pull very hard on electrons. It has a low electro negativity. So there is a big difference here. And the electro negativity is between these two atoms. And so what that means is that this bond that forms between them, which represents the sharing of two electrons, a pair of electrons. Because chlorine pulls harder on these two electrons, these two electrons are going to spend mawr time with the chlorine. And remember, the electrons are negatively charged. So because these two negatively charged electrons spend more time with the chlorine because the chlorine pulls harder on these electrons because it's more electro negative. Uh, the chlorine is gonna be associated with a partial negative charge because once again it's pulling these negatively charged electrons harder, and so they spend more time with the chlorine. And that's what gives the chlorine a partial negative charge. And the opposite happens to the hydrogen. The hydrogen does not pull as hard on the electrons because it is not as electro negative. And so it has these electrons for less amount of time. And so if you give up something that's negative, you therefore become more positive. And so it gets, Ah, partial positive charge. And so you can see how this unequal distribution of electrons between the atoms leads to partial charges. Now we can see something very, very similar if we take a look at a typical water molecules such as H, which is Who's chemical formulas H two up. It has two hydrogen atoms and one oxygen atom. Now, once again, oxygen is one of the most electro negative atoms that exists. It is super electro negative, which means that it pulls on these electrons super super hard. The hydrogen atoms, on the other hand, once again, are not very electro negative, so they do not pull on electrons that hard at all, and so Of course, each of these lines that we see here represent a pair of electrons being shared between the atoms so you can see down below. We have a pair over here and a pair over here being shared. And so because once again, oxygen pulls really, really hard on these electrons that are being shared, those electrons are going to spend more time with the oxygen. And because the electrons are negatively charged, it gives the oxygen a partial negative charge on it. And once again, the hydrogen, on the other hand, are gonna have partial positive charges. And this occurs on every single water molecule, uh, that exists here. Now. The last example that we have of polar Covalin bonds is ammonia, whose chemical formula is N H three. And once again you could see it has one nitrogen atom and three hydrogen atoms. The nitrogen atom is going to be much more electro negative than the hydrogen atoms, which are not very electro negative. And so this means that the nitrogen atom is going to pull harder on the electrons. There's a different electro negativity is once again. And so, uh, these electrons that are being shared here and here and here are going to spend more time with the nitrogen atom. And that gives the nitrogen atom a partial negative charge. And once again, the hydrogen zehr going to have partial positive charges. And so again, the main take away here is that polar Covalin bonds are due to unequal sharing of electrons and unequal sharing of electrons means that the distribution of electrons is going to be unequal is well, which leads to partial charges. And so over here on the far right, what we have is another image to help, uh, clear up this idea of polar Covalin bonds. So basically, you can think in polar Covalin bond because they are sharing electrons, but they're sharing them unequally. There's pretty much a bully here in this tug of war battle on the electrons. And there's gonna be one Adam that is much more electro negative than another Adam. That does not pull very hard on electron. So the electron that's being shared is going to spend mawr time with the Mawr electro negative, Adam, and that creates a partial negative charge and the atom that is kind of deprived of the negatively charged electron becomes slightly positively charged, partially positively charged. And so this all results from unequal sharing of this electron. And that's why you can see that the electron is closer to the more electro negative Adam, because it pulls harder on it. And so this year concludes our introduction to Polar Covalin bonds, and we'll be able to get some practice moving forward in our course, so I'll see you all in our next video.