4.25 6th edition: Polarity of SF4

[Elaine Pham 2E]

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]

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]

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]

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.

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[Hanniel U 2B]

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