Q. 6.82 - An Introduction to General, Organic, and Biological Chemistry

Question

Identify each of the following molecules as polar or nonpolar:
a. ${\mathrm{SeF}}_2$
b. ${\mathrm{PBr}}_3$
c. ${\mathrm{SiF}}_4$
d. ${\mathrm{SO}}_2$

Step-by-Step Solution

Answer

Part(a) ${\mathrm{SeF}}_2$is polar molecule.

Part(b) ${\mathrm{PBr}}_3$ is polar molecule.

Part(c) ${\mathrm{SiF}}_4$ is nonpolar molecule.
Part(d) ${\mathrm{SO}}_2$ is polar molecule.

Part(a) Step 1 : Given information

We have to identify  the ${\mathrm{SeF}}_2$ molecules as polar or nonpolar.

Part(a) Step 2 : Simplify

${\mathrm{SeF}}_2$ has polar properties.
It has a bent shape because it has two lone pairs and two bond pairs.

Part(b) Step 1 : Given information

We have to identify  the following molecules as polar or nonpolar.

Part(b) Step 2 : Simplify

Because of its asymmetrical form, ${\mathrm{PBr}}_3$ (phosphorus tribromide) is a polar molecule.
The difference in electronegativity is more than $0.5$, making the $\mathrm{P}-\mathrm{Br}$ bonds polar.
However, it is classified as a polar molecule due to its asymmetrical form.

Part(c) Step 1 : Given information

We have to identify  the ${\mathrm{PBr}}_3$ molecules as polar or nonpolar.

Part(c) Step 2 : Simplify

Because the fluorine atoms are organised in a tetrahedral molecule around the centre silicon atom, all of the negative charge regions cancel each other out, ${\mathrm{SiF}}_4$ is a nonpolar molecule.

Part(d) Step 1 : Given information

We have to identify  the ${\mathrm{SiF}}_4$ molecules as polar or nonpolar.

Part(d) Step 2 : Simplify

Sulfur dioxide ${\mathrm{SO}}_2$ is a polar substance.
Because of its bent molecular shape, the molecule exhibits a nonzero dipole moment.