Lewis Structures

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Claudeth Martinez 1D
Posts: 52
Joined: Fri Sep 28, 2018 12:18 am

Lewis Structures

Postby Claudeth Martinez 1D » Sun Nov 04, 2018 11:30 pm

hey,

Does anyone know how I can use Lewis structures to determine if a molecule is polar or nonpolar?

Haowen_Liang_3E
Posts: 20
Joined: Fri Apr 06, 2018 11:03 am

Re: Lewis Structures

Postby Haowen_Liang_3E » Sun Nov 04, 2018 11:35 pm

if you set up the Lewis structure correctly, and know your electronegativity, then you can figure which molecule keeps the shared e- longer (more negative). Then look at the angles and placement of those charged regions, if the charge molecules are skewed to one side, or not balanced with another charged molecule on the opposite side, then it is polar.

Laura Gong 3H
Posts: 89
Joined: Fri Sep 28, 2018 12:26 am
Been upvoted: 1 time

Re: Lewis Structures

Postby Laura Gong 3H » Mon Nov 05, 2018 1:24 pm

One easy way too tell if a molecule is non polar is if the atoms surrounding the central atom are all the same. For example CH4 is non polar.
Granted if there is a lone pair on the central atom and the atoms are the same around it, it will actually polar. For example, SO2.

Brian Chang 2H
Posts: 65
Joined: Fri Sep 28, 2018 12:17 am

Re: Lewis Structures

Postby Brian Chang 2H » Mon Nov 05, 2018 1:41 pm

Polarity is often linked with Symmetry.

CH4 is a tetrahedral molecule so it's charge is nicely balanced out between the 4 H atoms.

But H2O is bent because Oxygen has 2 bonding pairs and two lone pairs. So the lone side of the molecule is more negatively charged than the side with Hydrogen atoms. So it's a polar molecule.

This is also the explanation for the cohesion of water molecules.

Cheers.


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