Q. 6.72 - An Introduction to General, Organic, and Biological Chemistry

Question

 Choose the shape (1 to 6 ) that matches each of the following descriptions (a to c):

1. linear
2. bent (109∘)
3. trigonal planar
4. bent (120∘)
5. trigonal pyramidal
6. tetrahedral

a. A molecule with a central atom that has four electron groups and two bonded atoms
b. A molecule with a central atom that has two electron groups and two bonded atoms
c. A molecule with a central atom that has three electron groups and two bonded atoms

Step-by-Step Solution

Answer

Shapes according to given description are:

(a) Bent$(109°)$ ; Option $2$

(b) Linear ; Option $1$

(c) Bent $(120°)$; Option $4$

Part (a) Step 1: Given Information

We need to find shape of molecule according to description:

A molecule with a central atom that has four electron groups and two bonded atoms 

Part (a) Step 2: Explanation

A molecule with four electron groups on its central atom, two atoms bonded to it has two lone pairs and bond angle of $109°$. So shape of molecule is bent($109°$). Example ${\mathrm{H}}_2\mathrm{O}$. Hence. option $2$ is correct.

Part (b) Step 1: Given Information

We need to find shape of molecule according to description:

A molecule with a central atom that has two electron groups and two bonded atoms 

Part (b) Step 2: Explanation

A molecule with two electron groups on its central atom, two atoms bonded to it has zero lone pair and bond angle of $180°$. So molecule has linear shape. Example ${\mathrm{CO}}_2$. Hence. option 1 is correct.

Part (c) Step 1: Given Information

We need to find shape of molecule according to description:

A molecule with a central atom that has three electron groups and two bonded atoms 

Part (c) Step 2: Explanation

A molecule with three electron groups on its central atom, two bonded atoms to central atom will have one lone pair and bond angle of $120°$ . Shape of molecule is bent$(120°)$. Example ${\mathrm{SO}}_2$.

Hence. option 4 is correct.