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Difference Between Polar and Nonpolar Bonds

Posted: Sun Nov 01, 2015 1:02 am
by Jeffrey Wang
Could someone please explain why water, H2O, is a polar bond, whereas a molecule like CS2 is nonpolar? Don't the dipole moments in both the molecules end up cancelling each other equally?

Re: Difference Between Polar and Nonpolar Bonds

Posted: Sun Nov 01, 2015 9:41 am
by Du-A Lee 3C
H2O is a polar molecule because of the 2 lone pairs of e- on the central atom O. This makes this an angular/bent shape of molecule (dipole moments won't cancel).
CS2 is a nonpolar molecule because it is linear shaped (dipole moments cancel each other out).

Re: Difference Between Polar and Nonpolar Bonds

Posted: Sun Dec 06, 2015 2:11 pm
by JuliaPark2H
Adding on to the post above, in determining polarity, you want to look at all the VSEPR shapes depending on the number of electron density and how the number of lone pairs affects the shape of the molecule.
For CS2, it's nonpolar because the two double bonds that form between C and S create a linear shape, and since the same S atom is attached to either side, the pull from S's electronegativity cancels each other out, making it nonpolar.