IMAT 2014 Q52 Chemistry

Hello! Im having so much trouble with this question. I studied that permanent molecular dipoles occurs between covalent compounds with polarity. But sincerely, I don’t know what’s the best approach to this question, should I memorize the E.N of the main elements?
I though I knew about I.F until I ran into this :dizzy_face: So if you help me I’ll be really grateful
The answer is B :ok_woman:

This is how i solve these types of questions so, they have basically asked the molecule having a strongest permanent dipoles you can draw the Lewis structures of molecules in the answer options to check which ones have prominent dipole the symmetrical molecules (i.e ones having same atoms attached in equal no’s have no net dipole as they cancel out each other) in this question in every answer options we have a molecule which is exibiting symmetry except option 2 so by elimination we have our answer.

Another way of looking at it: Halogen atoms can form very strong covalent bonds, giving them the strongest permanent molecular dipole. B has two molecules with halogens in covalent bonding thus it is the correct answer.
Hope it makes sense:)



Thanks for your answer! Do you agree SiF4 does have a permanent molecular dipole because of it’s geometry (although not as strong as ICl or CH2Cl2) ?


I think it doesn’t have a prominent dipole as we know SiF4 has a tetrahedral geometry drawing it’s structure we have 4F atoms which are located at the corners of the tetrahedron surrounding the Si.
Having such a symmetrical arrangement of F atoms dipoles basically cancel out each other.
What’s your take on it?


thanks! i agree with you i just got confused when drawing the structures