Lewis structures that are not symmetrical

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Jorja De Jesus 2C
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Joined: Sat Jul 20, 2019 12:15 am

Lewis structures that are not symmetrical

Postby Jorja De Jesus 2C » Sat Nov 09, 2019 11:45 pm

If a lewis structure has atoms arranged around its central atom non-symmetrically then it is a polar atom right? What draws the line between symmetrical and not symmetrical? For example if there are 5 atoms around the central atom, the atoms could be arranged around it so that it can be either symmetrical (if it looks like an upright star) or not symmetrical (if it looks like a sideways star). How would you be able to tell if the molecule is polar or not?

305416361
Posts: 50
Joined: Fri Aug 09, 2019 12:17 am

Re: Lewis structures that are not symmetrical

Postby 305416361 » Sun Nov 10, 2019 12:17 am

I could be fully wrong here so if I am please someone else correct me:
I believe that polarity has to do with the distribution/sharing of electrons, so regardless of which way the structure is "turned" when drawn, if the electrons are distributed equally then it is non polar, and if they are shared unevenly, then it is polar

Anne Tsai 1F
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Joined: Thu Jul 25, 2019 12:15 am

Re: Lewis structures that are not symmetrical

Postby Anne Tsai 1F » Sun Nov 10, 2019 4:01 pm

I think polarity is determined by the difference in electronegativities between atoms in a molecule. However, symmetry does play a role with a molecule like CO2, which is nonpolar overall despite the charge differences between C and O because the oxygens pull on the carbon in the center equally and in opposite directions.

Dan M -3E
Posts: 101
Joined: Wed Sep 18, 2019 12:19 am

Re: Lewis structures that are not symmetrical

Postby Dan M -3E » Sun Nov 10, 2019 4:51 pm

I think for a single atom that has 5 electrons, it would still be considered nonpolar because the electrons move around the nucleus and end up being equally distributed, on average, around the because they move so fast around it.

Shail Avasthi 2C
Posts: 101
Joined: Fri Aug 30, 2019 12:17 am

Re: Lewis structures that are not symmetrical

Postby Shail Avasthi 2C » Mon Nov 11, 2019 11:12 pm

It depends on the molecule. When you arrange 5 identical atoms around a central atom (e.g. PF5), this molecule will be non-polar because of the shape of the molecule. You can also have a symmetrical molecule that is polar (e.g. CH2Cl2) due to dipole moments etc.. Symmetry is not a reliable way to determine polarity because there are many exceptions. The best way to tell if a molecule is polar or not is to look for dipole moments / lack thereof.


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