Polarity and positioning of atoms in Lewis Structures

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

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Shirley Liu 2I
Posts: 64
Joined: Fri Sep 28, 2018 12:16 am

Polarity and positioning of atoms in Lewis Structures

Postby Shirley Liu 2I » Sun Nov 25, 2018 10:29 pm

When finding the polarity of a molecule, we have to first draw the Lewis Structure of the molecule and then draw dipoles depending on the electronegativity difference between the central and outer atoms. However, wouldn't the position of the outer atoms matter, especially if they are different from each other? Wouldn't they be pulling the electrons in a different direction depending on the atom and the position of them in relation to the central atom, such as in a tetrahedral shaped molecule? Or does position of the different atoms around the central atom not matter?

Andrew Bennecke
Posts: 62
Joined: Fri Sep 28, 2018 12:15 am

Re: Polarity and positioning of atoms in Lewis Structures

Postby Andrew Bennecke » Sun Nov 25, 2018 11:24 pm

In a nonpolar Lewis Structure with a tetrahedral shape (CH4), we draw just as we have been drawing it since the dipoles cancel and each of the terminal atoms provide equal repulsion unto the central atom. However, in a Polar Lewis structure with a tetrahedral shape (CClH3), we should draw the structure with a slight variation in bond angle away from the polar atom or away from the lone pair of electrons, such as in NH3 (Shape changes to Trigonal Pyramidal).

Ronak Singh
Posts: 31
Joined: Fri Sep 28, 2018 12:16 am

Re: Polarity and positioning of atoms in Lewis Structures

Postby Ronak Singh » Mon Nov 26, 2018 12:11 pm

The position of atoms around the central atom doesn't matter because all of the bond angles are the same.


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