Question

1. Finish drawing the Lewis structures of the following molecules and then tell how many sigma and pi bonds and how many bond pairs and lone pairs there are in cach. H 0 a) HC-CC-H 2. Which of the following is not a likely Lewis structure for HNO: ? Why? H-OEN H_0 No ::: ::

Answer 1

1.

(a).

Drawing lone pairs on the oxygen atom completes the Lewis structure.

H :O: H H - C- –c JC -H. I

All single bonds are sigma bonds. Double bond consists of one sigma and one pi bond.

The number of single bonds in the above structure = 8

The number of double bonds in the above structure = 1

Hence, the number of sigma bonds = (8 + 1) = 9

The number of pi bonds = 1

Number of bond pairs = number of bonds = 10      (each bond is made up of 2 electrons)

Only oxygen has two lone pairs in the above structure.

Hence, the number of lone pairs = 2

(b).

Drawing lone pairs on the oxygen and nitrogen atoms completes the Lewis structure.

10:

All single bonds are sigma bonds. Double bond consists of one sigma and one pi bond.

The number of single bonds in the above structure = 6

The number of double bonds in the above structure = 1

Hence, the number of sigma bonds = (6 + 1) = 7

The number of pi bonds = 1

Number of bond pairs = number of bonds = 8    (each bond is made up of 2 electrons)

Oxygen has two lone pairs and each nitrogen has one lone pair in the above structure.

Hence, the number of lone pairs = 4