[sammiegirl]

Which one of these molecules has bonds that are the most polar? Which have a molecular dipole moment?

F2
CF4
BrCl
SF4
PF3


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Okay so i believe the answer to the first questions is PF3 because this have the largest difference in electronegativities.  Part two confuses me, i understand that a molecule can have polar bonds but not be a polar molecule.  I believe that only BrCl has a molecular dipole moment.  All of the other ones are either not polar (F2) or  the polar arrows counterbalance each other.  Thanks!

[Hbond]

Your answers are correct. The higher electronegativity difference will create the stronger polar bond. The second question has to do with geometry. If all the perimeter atoms are all negative or all positive there is no place on the perimeter this is both positve and negative. Only BrCl  have both positive and negative at the perimeter.