Question

Draw Lewis structures and predict the molecular structures of the following. (See Exercises 97 and 98.)

a. OCl₂, KrF₂, BeH₂, SO₂

b. SO₃, NF₃, IF₃

c.CF₄, SeF₄, KrF₄

d. IF₅, AsF₅

Which of the above compounds have net dipole moments (are polar)?

Short answer

Lewis structure of the molecules and molecular structure

a. OCl₂

Bent shape

This molecule has a net dipole moment and they are polar because of their structure.

KrF₂

Linear

This molecule does not have a dipole moment. They are nonpolar because both bonds are in opposite directions

to cancel each other out.

BeH₂

Linear

This molecule does not have a simple moment because of its linear structure.

SO₂

V-shaped and bent

It has a net dipole moment because of its asymmetrical charge distribution.

b. SO₃

Trigonal planar

Net dipole moment zero because of symmetry

NF₃

Tetrahedral

It is polar and has a net dipole moment

IF₃

Trigonal bipyramidal

The molecule is asymmetrical and has a net dipole moment

c. CF₄

Tetrahedral

Because the molecule is symmetrical, it does not have a net dipole moment.

SeF₄

See-Saw

It has a net dipole moment because it is asymmetrical.

KrF₄

Square planar

It has no net dipole moment because it is symmetrical.

d. IF₅

Square pyramidal

It has no net dipole moment because it is symmetrical

AsF₅

Trigonal bipyramidal

It has no net dipole moment because it is symmetrical

Step-by-step solution

Step-1 Drawing  lewis structure

Draw the lewis structure of the given molecules with help of the octet rule which states that the outermost shell of the valence electron can contain 8 electrons.

Step-2 Drawing molecular structure to find the symmetry of molecules

With the help of VSEPR theory, draw the molecular structure of given molecules taking stability, lone pairs electrons, electronegativity and bond pairs electrons in mind. With the help of molecular structure, we can find the net dipole moment of the molecules, as we all know that asymmetrical structure has a dipole moment and symmetrical structure does not contain any dipole moment.