Question

Question:For each of the answers in Problem 59,state whether the species is polar or nonpolar.

Short answer

Polar structures for the given species are${\text{SOCl}}_{\text{2}}$and${\text{ICl}}_{\text{3}}$. Nonpolar structure for the given species are$\left({\text{CBr}}_{\text{4}}{\text{,SO}}_{\text{3}}{\text{,SeF}}_{\text{6}}\right)$.

Step-by-step solution

Step 1: Rule of thumb

Chemical systems or components with a centrally symmetric symmetry are usually nonpolar. A more precise explanation is as follows: a structure is nonpolar if the total of its dipole moments (vectors) is zero. This can be accomplished in two ways: either the geometry allows the vectors to " cancel out" during the summation, or the dipole moments are set to zero.

The first indicates that the structure is centrally symmetric (assumed that the vectors are of equal length); the second indicates that the bonds are between atoms of the same element.

Step 2: Polar species

Polar structures are ${\text{SOCl}}_{\text{2}}$and${\text{ICl}}_{\text{3}}$.

The graphics below show the molecules' approximate overall dipole vectors (orange). The so-called "MEP surface" is depicted in the case of thionyl chloride; hues toward the red end of the spectrum imply a negative charge in a polarised structure.

Step 3: Nonpolar species

Because their respective polyhedra (or polygon in the case of planar sulfur trioxide) are regular -$\left({\text{CBr}}_{\text{4}}{\text{,SO}}_{\text{3}}{\text{,SeF}}_{\text{6}}\right)$- all of the other structures are perfectly symmetrical.

As a result, their overall dipole moments are zero.