Question

Predict the shape and bond angles in the following molecules :

a. CF₄

b. NF₃

c. HCN 

d. H₂S

Answer 1

a. CF₄ :

There are four bond pairs on the central atom.

Hence,

Shape of CF₄ is tetrahedral and F-C-F bond angle is 109° 28′.

b. NF₃ :

There are three bond pairs and one lone pair on the central atom. 

Hence,

Shape of NF₃ is trigonal pyramidal and F-N-F bond angle is less than 109° 28′.

c. HCN :

There are two bond pairs on the central atom. 

Hence, 

Shape of HCN is linear and H-C-N bond angle is 180°.

d. H₂S :

There are two bond pairs and two lone pairs on the central atom. 

Hence, 

Shape of H₂S is bent or V-shaped and H-S-H bond angle is slightly less than 109° 28′.