2E.25

[Amy Luu 2G]

Draw the Lewis structure and predict whether each of the following molecules is polar or nonpolar (d) SF4
I drew the Lewis structure which had S as the central atom and 4 F single bonded to S. There is also a lone pair on S. How do I know if this is polar or nonpolar?

[Ally Huang- 1F]

Since there is a lone pair on the central atom, it is usually polar. Usually an odd number of lone pairs on the central atom makes it polar. Also, since SF4 shape is see saw, two of the SF bond dipoles cancel each other out because they are 180 degrees from each other. The other two SF bonds point down, so their bond dipoles don't cancel. The asymmetrical charge distribution makes it polar.

[April Pazos 3D]

When trying to find out if a molecule is polar or non-polar, write all the dipole moments and see if they cancel out. If the dipole moments do not cancel out, then the molecule is polar. If the dipole moments do cancel out, then the molecule is non-polar. Since SF4 has 4 bonds and one lone pair, the lone pair repels the bonds and causes 2 dipole moments to cancel out while the other two don't.