Q11.58CP - Chemistry: Molecular Nature Of Matter And Change

Question

Acetylsalicylic acid (aspirin), the most widely used medicine in the world, has the Lewis structure at the right.

1. What is the hybridization of each  $\mathbf{C}$  and each  $\mathbf{O}$ atom?
2. How many localized  $\mathbf{\pi }$ bonds are present?
3. How many  $\mathbf{C}$ atoms have a trigonal planar shape around them? A tetrahedral shape? 

 

Step-by-Step Solution

Answer

Hybridization provides a hybrid state for the overlapping of electrons to maximize stability.

 

The answer for

(a). ${\mathbf{sp}}^2$ and ${\mathbf{sp}}^3$ for carbon,  ${\mathbf{sp}}^2$  and ${\mathbf{sp}}^{\mathbf{3}}$for oxygen

(b). 5 $\mathbf{\pi }$  bonds.

(c). 8 and 1

Step 1: Definition

The atomic orbitals fuse to form new orbitals with completely different energies, shapes, and so on.

 

Atomic orbitals are mixed together to create hybrid orbitals. The total number of hybrid orbitals is equal to the number of bond pairs + the number of lone pairs on the main atom.

Step 2: For hybridization of each C and each O

All  $\mathbf{C}$ atoms are ${\mathbf{sp}}^2$   hybridized as it is surrounded by three bond pairs except $\mathbf{C}$  the atom in  ${\mathbf{CH}}_{\mathbf{3}}$  is ${\mathbf{sp}}^3$   hybridized as it is surrounded by four bond pairs.

The two  $\mathbf{C}\mathbf{=}\mathbf{O}$ groups are ${\mathbf{sp}}^2$   hybridized as it is surrounded by one bond pair and two lone pairs whereas the rest of $\mathbf{O}$ the atoms is   ${\mathbf{sp}}^3$ hybridized as it is surrounded by two bond pairs and two lone pairs.

Step 3: For the total number of π bonds

One sigma bond and one pi bond are present in a double bond. There are a total of five double bonds in the structure so it contains 5 $\mathbf{\pi }$  bonds.

Step 4: For shapes of carbon atoms

There is a total of 9 carbon atoms in the structure out of these 8 carbon atoms are surrounded by three bond pairs having ${\mathbf{sp}}^2$  hybridization with trigonal planar shape except for one carbon atom in the methyl group which is surrounded by four bond pairs having ${\mathbf{sp}}^{\mathbf{3}}$  hybridization with tetrahedral shape.