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Polar Tetrahedral Molecule CH2Cl2

Posted: Wed Nov 28, 2018 4:32 pm
by Chem_Mod
Why is CH2Cl2 polar?

To address a question received during office hours, I will use the example of CH2Cl2. When you draw its lewis structure, it may be easy to think that you can draw the molecule so that the C-Cl bonds are opposite to each other and the C-H bonds are opposite to each other, yielding a nonpolar molecule. However, one thing to remember is that the molecule is tetrahedral, and its bonds don't reside in the same plane. No matter how you draw your lewis structure, the 3-D structure will still be the same as the one below (it will just be rotated and viewed from a different angle). If this doesn't make sense to you, try drawing it out.

Image

Re: Polar Tetrahedral Molecule

Posted: Wed Nov 28, 2018 4:35 pm
by aisteles1G
If you draw the Hs across from each other and the Cls across from each other around the C atom the dipole moments will cancel out. Remember that you dont have to draw them in order of how they are written around the center atom so if drawn across from instead of next to the same atom the dipole moments cancel out leading to a non polar molecule. Hope this helps!