Polarity and dipole moments

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

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Ghadir Seder 1G
Posts: 134
Joined: Sat Sep 14, 2019 12:17 am

Polarity and dipole moments

Postby Ghadir Seder 1G » Tue Nov 26, 2019 8:43 pm

Can help clarify when dipole moments cancel out? I'm confused as to how they cancel :(

Kristina Rizo 2K
Posts: 105
Joined: Wed Sep 18, 2019 12:19 am

Re: Polarity and dipole moments

Postby Kristina Rizo 2K » Tue Nov 26, 2019 9:08 pm

Don't they cancel each other out when the molecule is symmetrical?

Reina Robles 2B
Posts: 71
Joined: Fri Aug 09, 2019 12:16 am

Re: Polarity and dipole moments

Postby Reina Robles 2B » Tue Nov 26, 2019 9:13 pm

The dipole moments cancel out when they're facing in opposite directions. If there's a diagonal dipole, I like to break them up into the two directions it's made of (up-right, down-right, etc.) and then check if any of the other dipoles cancel it out.

I hope this helps!

Osvaldo SanchezF -1H
Posts: 122
Joined: Wed Sep 18, 2019 12:21 am

Re: Polarity and dipole moments

Postby Osvaldo SanchezF -1H » Tue Nov 26, 2019 10:14 pm

Dipole moments cancel each other in other forms besides being symmetrical which is one of the easiest way to identify this but only occurs when all the surrounding atoms are the same. But generally there has to be an even number of the same atom in a molecule for anything to even cancel out because if there isn't there is a disruption in electronegativty which will make one specific atom attract or even less electrons than the others. Then you wanna make sure that their is no uneven disproportion of lone pairs that will affect the polarity of electrons to each other. After you check all of that, just make sure that the difference in electronagtivity isn't to great of the difference in atoms(if applicable) and make sure the charge goes in opposite direction of each other. I know it is long but with some examples and practice, it should become second nature to you.

ABombino_2J
Posts: 102
Joined: Thu Jul 11, 2019 12:15 am

Re: Polarity and dipole moments

Postby ABombino_2J » Tue Nov 26, 2019 11:58 pm

A dipole cancels when a molecule has no lone pairs and the same attachments. It also will cancel when the net dipole moments cancel when they are facing the opposite directions. In addition, it is important to know that 2-3 linear geometry and square planar are non-polar when they have the same attachments even though they have lone pairs.

Andrew Liang 1I
Posts: 105
Joined: Fri Aug 30, 2019 12:18 am

Re: Polarity and dipole moments

Postby Andrew Liang 1I » Wed Nov 27, 2019 12:02 am

The dipole cancels out when they are exactly opposite of each other and that they are the same atom because different atoms have different dipole force. The only way for a tetrahedral to have no dipole is when all 4 atoms are the same because based on the VSEPR model none of the atoms are points directly opposite of one another.

Justin Quan 4I
Posts: 104
Joined: Sat Sep 14, 2019 12:17 am

Re: Polarity and dipole moments

Postby Justin Quan 4I » Wed Nov 27, 2019 11:38 am

Kristina Rizo 3K wrote:Don't they cancel each other out when the molecule is symmetrical?

To add on, dipole moments will cancel out when the molecule is symmetrical and the surrounding atoms are identical. For example CH4 and CH3Cl are both tetrahedral, but CH3Cl is polar while CH4 is non-polar.

lauraxie2e
Posts: 108
Joined: Fri Aug 09, 2019 12:17 am

Re: Polarity and dipole moments

Postby lauraxie2e » Wed Nov 27, 2019 12:24 pm

It is mostly when the structure is symmetrical.

Hailey Kim 4G
Posts: 110
Joined: Sat Jul 20, 2019 12:16 am

Re: Polarity and dipole moments

Postby Hailey Kim 4G » Wed Nov 27, 2019 3:48 pm

Dipole moments cancel out in non-polar molecules. This means that the molecule is symmetrical. Polar molecules have dipole moments because there is a separation of charge. Tetrahedral molecules are only non-polar when all four atoms bonded to the central atom are the same element.


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