Polar/Non Polar 4.25d

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

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Colette Ussery 3L
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Polar/Non Polar 4.25d

Postby Colette Ussery 3L » Fri Nov 04, 2016 4:42 pm

Hi for chapter 4 question 4.25 we are supposed to write a lewis structure and determine whether or not the molecule is polar or non polar.
For part d I drew the lewis structure for SF4 and I thought that it would be nonpolar because there are 4 dipole arrows going in four different directions, but apparently the molecule is actually polar. Could someone please explain why? Thanks

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Re: Polar/Non Polar 4.25d

Postby Brandon_Phan_3J » Fri Nov 04, 2016 5:29 pm

I think where you might have made an error was how you drew the lewis structure of SF4. Since SF4 has an expanded octet, it would have one lone pair around the central sulfur and it would have a see-saw molecular shape, not a tetrahedral shape (which would indicate a nonpolar molecule). Since SF4 has a see-saw shape it is asymmetric and the charges on the atoms would not be equally distributed, this would cause the molecule to be polar.

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Re: Polar/Non Polar 4.25d

Postby Aya_Elarid_2H » Fri Nov 04, 2016 9:34 pm

SF4 is VSEPR geometry of atom is a seesaw the two arrows in the bottom of the lewis structure don't cancel out making it polar. The electronegativity of F is around 4.0 and S is around 2.5, the electronegativity difference is greater than 0.5 making it polar. F has a partial negative charge, while S has a partial positive charge making the bond a polar charge.

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