Polar vs. Nonpolar

(Polar molecules, Non-polar molecules, etc.)

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Brandon Tao 1K
Posts: 100
Joined: Sat Aug 17, 2019 12:15 am

Polar vs. Nonpolar

Postby Brandon Tao 1K » Sun Nov 24, 2019 10:15 pm

I took the test Friday and was really confused by a problem. If a molecule has 4 of the same bond atoms then it is non-polar(CH4). That is because the electronegativity values are the same. However if there are two of the same and two different shouldn't it also be non-polar? Sure the electronegativities are different but they should still cancel out? Someone mentioned the net dipole moments not being the same but I am still confused. Let's use CCl2H2 for instance.

Bilal Pandit 1J
Posts: 98
Joined: Wed Sep 11, 2019 12:16 am

Re: Polar vs. Nonpolar

Postby Bilal Pandit 1J » Sun Nov 24, 2019 10:20 pm

The reason that molecule is polar is that the shape is tetrahedral, which means the two Cl atoms aren't going to be opposite of each other. Since they aren't opposites of each other, they will not cancel out and as a result, the molecule will have a net dipole

Jennifer Yang 3F
Posts: 56
Joined: Wed Sep 11, 2019 12:17 am

Re: Polar vs. Nonpolar

Postby Jennifer Yang 3F » Sun Nov 24, 2019 10:22 pm

If you look at its VSEPR structure, you can see that the dipole moment do not cancel out.

Posts: 107
Joined: Fri Aug 09, 2019 12:17 am

Re: Polar vs. Nonpolar

Postby JChen_2I » Sun Nov 24, 2019 10:59 pm

if a central atom has two different pairs of elements attached to it, those dipoles would not cancel out because of the molecule's tetrahedral shape. The atoms are not all on one plane

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