Question

Which of the following is a polar molecule?
A. $B{{F}_{3}}$
B. $S{{F}_{4}}$
C. $Si{{F}_{4}}$
D. $Xe{{F}_{4}}$

Answer 1

Hint: It has an unsymmetrical see-saw structure. It is a colorless corrosive gas that releases dangerous HF upon exposure to water or moisture. Despite these unwelcome characteristics, this compound is a useful reagent for the preparation of organofluorine compounds, some of which are important in the pharmaceutical as specialty chemical industries.

Complete step by step answer:
A polar molecule is one where some of the atoms are more electronegative, that is they attract electrons more than the other atoms. As a result, the electrons in the molecule are dragged closer to one side of the molecule, making a positively charged side and a negatively charged side. The most famous polar molecule is water.

The most important polar molecule on Earth is water. Water is a polar molecule due to the strong electronegativity of the oxygen atom. This forces most of the electrons to the side of the molecule where oxygen is present, creating a highly negative area. The other side of the molecule becomes more positive, due to the protons of the hydrogen atom. Because water is a polar molecule which can interact with other water molecules therefore, it creates a more stable structure.

Now, let’s see why $S{{F}_{4}}$is a polar molecule!
$S{{F}_{4}}$Is a polar molecule as the individual bond dipoles do not cancel each other. It contains 4 bond pairs of electrons and 1 lone pair of electrons. S atom undergoes $s{{p}^{3}}d$ hybridization which results in distorted tetrahedral geometry. Here, $S{{F}_{4}}$ bond angles are around 102 degrees in the equatorial plane and around 173 degrees between the axial and equatorial positions.

Therefore, $S{{F}_{4}}$ is a polar molecule.

Note: Bonding electron pairs have lesser repulsions as compared to lone pair electrons. Sulfur Tetrafluoride does not follow the octet rule. It will hold more than 8 electrons. Sulfur having valence electrons in the 3rd energy level, will also have access to the 3rd sublevel, thus following for more than 8 electrons.