 Okay, so this is similar to the last problem we did, but I think it'll be good for us to be able to compare this one and this one Prepare this to like CH4 or CCl4 and this to like the last one we did SCL2 So let's try these. Okay, and CL3 so you know that N has The five valence electrons like that Cl needs just one valence electron. So what you'll find is that you'll make a bond like this And in fact you'll make Cl bonds So you got to know that you've got one two three four electron groups around that nitrogen Okay, one of them being a lone pair. So this bond angle here Is going to be 107.3. So this is a Trigonal pyramidal structure So now what we want to do is figure out the electronegativity difference between N and Cl Unfortunately, there is no electronegativity difference. So N is 3.0 and Cl is 3.0 So None of these bonds are polar Okay So this inherently is a non polar molecule. Ebr3 Notice P is in the same family as N is Br is in the same family as Cl is So they're going to look exactly the same these structures are going to look exactly the same Trigonal pyramidal E It's electronegativity is 2.1 Br's electronegativity is 2.8 So the difference in electronegativity of this bond is 0.7 divided Br is greater electronegativity. So The dipole arrow look like that. That's just for the bond So imagine the dipole arrow for this one would look the same And this one would look the same like that. So they're all going down So we have a partially positive center up here and down here Bottom here is partially negative. So the polarity of this molecule overall polarity Will look like that. So negative down here positive up here. So this is a polar molecule Cf4 It's good to compare this even to these okay, this Cf4 as well as four electron groups around it So but since it's got four things bonded to it Like carbon always does It has to be tetrahedral in nature. So in this molecule We've got C which is 2.5 divide and F which is 4.0 So every one of these bonds is 1.5 divide When we look at this we know well, we've got the exact same dipole arrow for every one of these bonds going out from the carbon to the fluorine and they're all going to be going out at Electronegativity difference of 1.5 Okay, but since they're all going from the central atom out They're canceling each other out. Okay, so all of these are Antagonists to each other. So all of them are canceling each other out and overall the molecule is going to be Non-fold it really helps if you have a little model to see The tetrahedral nation now look let's look at water water is another good one to compare to Cf4 and To Pvr3 because all three of these molecules have four electron groups Okay, but they differ in the amount of bonds that they have and the amount of lone pair electrons Since we've got two non-bonding pairs of electrons and two bonding pairs of electrons Well, we find is these squished down more than the ideal 109 and a half degrees to make this bond angle 104.5 degrees When we take the difference in electronegativity we find that oxygen is 3.5 Hydrogen is 2.1 So the overall difference in electronegativity is going to be 1.4 the box in this case The positive charge is going to be located on the hydrogen So we're going to have two dipole arrows. So two bonds That are equal in magnitude of difference of electronegativity So the combined of those two is going to create a positive region down here So delta positive and a negative region here making the overall dipole arrow