4.25 6th edition: Polarity of SF4

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

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Elaine Pham 2E
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4.25 6th edition: Polarity of SF4

Postby Elaine Pham 2E » Sat Nov 24, 2018 12:26 pm

For question 4.25 in the 6th edition of the textbook, why is SF4 polar? I thought since the dipole moments pointing towards F cancel out, the molecule would be nonpolar.

Saima Salam 3J
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Re: 4.25 6th edition: Polarity of SF4

Postby Saima Salam 3J » Sat Nov 24, 2018 1:13 pm

It has to do with electronegativity. The difference in electronegativity between Sulfure and Fluorine is 2.98 and the electronegativity is large enough for it to be a polar molecule.

Elaine Pham 2E
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Re: 4.25 6th edition: Polarity of SF4

Postby Elaine Pham 2E » Sat Nov 24, 2018 3:27 pm

But wouldn’t the polarity between Sulfur and Fluorine overall “cancel out” to result in an overall nonpolar molecule? The dipole moments are all equal and pointing in opposite directions so won’t they “cancel out”? Does it have anything to do with the fact that Sulfur has a lone pair in the molecule?

Chris Freking 2G
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Re: 4.25 6th edition: Polarity of SF4

Postby Chris Freking 2G » Sat Nov 24, 2018 3:41 pm

SF4 has the AXE notation AX4E. Therefore it has the see-saw molecular shape which is asymmetric and the dipole moments do not cancel out.

Screen Shot 2018-11-24 at 3.35.29 PM.png
Screen Shot 2018-11-24 at 3.35.29 PM.png (9.24 KiB) Viewed 213 times

Hanniel U 2B
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Re: 4.25 6th edition: Polarity of SF4

Postby Hanniel U 2B » Sat Nov 24, 2018 3:52 pm

The electronegativity difference between S and F is greater than 0.5, that's why it is Polar.


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