Determine whether each molecule is polar or nonpolar. c. BrCl₅

Video transcript

Hey everyone. So today we're trying to identify the polarity of PCO. five or phosphorus Penta chloride. I find that the easiest way to identify the polarity of a molecule is by drawing out its lower structure. And to do this we first need to find out how many valence electrons are present within the molecule. So let's take a look at the first atom or element phosphorus. So phosphorus is a group five element which means that it will have five valence electrons or five electrons in its outermost orbital. Similarly Chlorine is a group seven element. It is a halogen which means it will have seven valence electrons. So telling this up, we have five valence electrons from the phosphorous Plus five times 7 because there are five chlorine Which leaves us with 40 valence electrons. Now that we have this we can go ahead and start drawing our molecules so we keep phosphorus as a central atom. We can connect it to five chlor Ian's via single bonds keep in mind that each single bond is 10 or sorry each single bond is too electrons. So that means for five single bonds. We will have 10 valence electrons in five single bonds. Now that means that we still have 30 valence electrons. We need to add to our Lewis structure. We can do this by filling the octet of each of the chlorine. Doing this adds three lone pairs or six total electrons to each of the Koreans And since there are six Or five groups of six electrons that we're adding. We have five times six or 30 electrons that we've added in total to the molecule 30 selections for oct. It's So now we have no more electrons to work with because now we have all 40 valence electrons. So now that we have our Lewis structure, we can then go ahead and take a look at the polarities themselves. So let's take a look at the phosphorus chlorine bond. So we can recall that our electro negativity trend on the periodic table increases from the bottom left to the top right of the table. Since chlorine is further to the right than phosphorus, it'll be more electro negative, which means it will have a diaper moment going towards the chlorine as it will attract more of the electrons. Therefore, each of the P C. O bonds are all polar. However, due to the symmetrical nature of the molecule, the diaper moments actually cancel out. Which means that even though each bond is polar, PCR five, he's non polar. It is a non polar molecule due to the symmetry. I hope this helps