Question

The molecules ${\mathrm{CH}}_4$and ${\mathrm{CH}}_3\mathrm{Cl}$both have tetrahedral shapes. Why is ${\mathrm{CH}}_4$ nonpolar whereas ${\mathrm{CH}}_3\mathrm{Cl}$ is polar?

Short answer

${\mathrm{CH}}_4$is nonpolar and ${\mathrm{CH}}_3\mathrm{Cl}$ is polar due to dipole moment.

Step-by-step solution

Given information

We are given that both ${\mathrm{CH}}_4$and ${\mathrm{CH}}_3\mathrm{Cl}$ have tetrahedral shape.

Simplify

In ${\mathrm{CH}}_4$all of the atoms around the centre element (carbon) in a molecule of methane are equal (four hydrogens), and thus has a net dipole moment of $0$. (vectors of dipole moments cancel each other, dipole moment is zero). but There are various elements (one chlorine and three hydrogen atoms) surrounding the centre atom (carbon) in the chloromethane ${\mathrm{CH}}_3\mathrm{Cl}$molecule, and thus has a greater net dipole moment. Therefore ${\mathrm{CH}}_4$is nonpolar whereas ${\mathrm{CH}}_3\mathrm{Cl}$ is polar.