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Polar VS Nonpolar shapes

Posted: Sun May 27, 2018 11:39 pm
by sylvie_1D
Hi, so for non polar molecules I understand that there must be dipole forces that cancel each other out, though what exactly does this mean and how do they "cancel". Do the dipole moments have to be equal in strength or do there simply have to be "dipole moments".

Re: Polar VS Nonpolar shapes

Posted: Sun May 27, 2018 11:52 pm
by Garrett Dahn 1I
Sylvie--

The dipole moments of non polar molecules will cancel out insofar as the individual dipole vectors will literally cancel out: two perfectly horizontal dipole vectors going in opposite directions ( --> <--) would, for example, cancel out. The vectors cancel the way a vector in physics might cancel -- a force going one way can offset a force going in the exact opposite way. For this reason, the dipole moments should need to be of equal strength to cancel each other out in the way that gravitational force and normal force cancel out on earth to keep us on the ground.

Hope this can help!

Re: Polar VS Nonpolar shapes

Posted: Tue May 29, 2018 6:01 pm
by Ignacio Ramirez 1J
If a molecule is completely symmetric, then the dipole moment vectors on each molecule will cancel each other out, making the molecule nonpolar. A molecule can only be polar if the structure of that molecule is not symmetric. Dipole moments need to have equal strength.

Re: Polar VS Nonpolar shapes

Posted: Wed Jun 06, 2018 3:54 pm
by Salena Chowdri 1I
The dipole moments have to be equal in strength, so 2 of the same bonds can cancel each other out. "Cancel" here means opposing vectors. However, when you're considering whether a compound is polar or nonpolar always think of the structure in 3D.

Re: Polar VS Nonpolar shapes

Posted: Thu Jun 07, 2018 11:01 am
by Daniel Cho Section 1H
In addition, the polarity is focused on the electronegativity negativity. So compounds like F2 is nonpolar because their electronegativity difference is very small. It also depends on the molecular shape but you more so have to draw it out to see if any of the dipole moments cancel out.

I hope this helps. Please correct me if I am wrong in certain places.