Question

Question:For each of the answers in Problem 60, 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 structures 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.

Polar species

Both the molecules${\text{PF}}_{\text{3}}$ and ${\text{SO}}_{\text{2}}{\text{Cl}}_{\text{2}}$are polar. Also${\text{ClO}}_{\text{2}}^{\text{-}}$, the anion has polar structures.

The graphics below show the molecules' approximate overall dipole vectors (orange). Despite the overall negative charge, the bent anion must have an unequal distribution of electrons: the oxygen atoms hold the majority of the charge. Lewis resonance structures are a good example.

Nonpolar species

Because their respective polyhedra are regular, the other two structures$\left(\text{P}{{\text{F}}_{\text{6}}}^{\text{-}}{\text{,GeH}}_{\text{4}}\right)$are exactly symmetrical.

As a result, their overall dipole moments are zero.