CH2Cl2

[lauraxie2e]

Does anyone know why when we draw the lewis structure for this we draw the hydrogens next to each other and the chlorines next to each other instead of across from each other, because if we have them next to each other I understand why there is dipole dipole attraction forces, but if they were across then wouldn't it be only London dispersion?

[Chem_Mod]

When drawing lewis structures, the arrangement in that case does not matter because everything is attached to the Carbon. Remember that the real structure is 3 dimensional, so any 2 dimensional drawing should be fine.

[Paul Hage 2G]

Because CH2Cl2 is tetrahedral-shaped, the bond angles would be around 109.5 degrees. Therefore, no matter how the Lewis structure is drawn, the dipole moments will still be going towards chlorine in different directions, so the dipole moments would not cancel.

[JOtomo1F]

This is where people get tripped up on from Lewis structures and determining if a molecule is polar or non-polar. Even though the drawing may look as if the dipoles are cancelling, you must refer to the VSEPR model in order to see the actual angles and where the bonds are.