00:01
So now we're going to work on problem 71 from chapter 5.
00:07
In this problem, we're asked to determine whether the molecules which are discussed in an earlier problem, problem 57, are polar or non -polar.
00:23
So the first molecule from problem 57 is phosphorus trifluoride pf3.
00:33
So here we can go ahead and draw the lewis structure.
00:41
This molecule will have 26 electrons total.
00:51
So after we've assigned all of the lone pairs to the fluorines, there's two electrons left over for phosphorus.
01:03
So we need to first recognize here that we have a polar bond.
01:10
The p and f bond will be a polar bond.
01:16
And then after that we need to see if these cancel, will they cancel.
01:27
So the phosphorus fluoride bond is going to pull in opposite directions, or not equally in opposite directions.
01:37
So they don't cancel.
01:40
And also we have the presence of a loan pair.
01:43
So since because of these two facts, the molecule is a polar molecule.
01:59
In part b, we're given sbr2.
02:07
Here, we have sulfur as our central atom connected to two.
02:14
Bromine atoms.
02:18
And after we assign all the lone pairs to bromine, we have two pairs of electrons left, which we assign to the sulfur atom...