Q11.53CP - Chemistry: Molecular Nature Of Matter And Change

Question

There is concern in health-related government agencies that the American diet contains too much meat, and numerous recommendations have been made urging people to consume more fruit and vegetables. One of the richest sources of vegetable protein is soy, available in many forms. Among these is soybean curd, or tofu, which is a staple of many Asian diets. Chemists have isolated an anticancer agent called genistein from tofu, which may explain the much lower incidence of cancer among people in the Far East. A valid Lewis structure for genistein is NN

1. Is the hybridization of each  $\mathbf{C}$ in the right-hand ring the same? Explain.
2. Is the hybridization of the $\mathbf{O}$  atom in the centre ring the same as that of the $\mathbf{O}$  atoms in  $\mathbf{OH}$groups? Explain.
3. How many carbon-oxygen  $\mathbf{\sigma }$ bonds are there? How many carbon-oxygen  $\mathbf{\pi }$ bonds?
4. Do all the lone pairs on oxygens occupy the same type of hybrid orbital? Explain.

Step-by-Step Solution

Answer

For the $\mathbf{sp}$  hybridization one  $\mathbf{s}$ and $\mathbf{p}$  orbitals are mixed together.

The orbital hybridization of a central atom that has one lone pair-bonded to two other atoms are  ${\mathbf{sp}}^{\mathbf{2}}$ hybridized.

The answer for

1. Same
2. Same
3. 6 $\mathbf{\sigma }$ and 1 $\mathbf{\pi }$ 
4. No

Step 1: Definition

Hybridization is the process of the formation of new atomic orbitals with stable bonds by the mixing of different atomic orbitals.

 

In this process, the total number of hybrid orbitals equals the total number of atomic orbitals as well as it is the sum of the total lone pair on the central atom and the total number of atoms bonded to the atom.

 

Step 2: For the hybridization of each C in the right-hand ring .

Here, all the $\mathbf{C}$  in the right-hand ring is surrounded by three electron groups i.e., three bond pairs. Thus, all the  $\mathbf{C}$ -atoms are ${\mathbf{sp}}^{\mathbf{2}}$  hybridized.

Hence, the hybridization of each  $\mathbf{C}$ in the right-hand ring is same.

 

Step 3: For the hybridization of O atom in the centre ring.

Here, the $\mathbf{O}$   atom in the centre ring as well as the  $\mathbf{O}$ atoms attached to OH groups are surrounded by four electron domains i.e., two bond pairs and two lone pairs. Thus, the $\mathbf{O}$  atoms are   ${\mathbf{sp}}^{\mathbf{2}}$ hybridized.

 

Hence, the hybridization of the $\mathbf{O}$  atom in the centre ring the same as that of the  $\mathbf{O}$  atoms in $\mathbf{OH}$  groups is the same

 

Step 4: For σ and π bond in carbon-oxygen

When atomic orbital overlaps head-to-head sigma bond is formed and an overlaps lateral pi bond is formed. There are 6 $\mathbf{\sigma }$ and 1 $\mathbf{\pi }$   bonds between carbon-oxygen bond

 

Step 5: For the lone pairs of oxygen

All the lone pairs on oxygens occupy the same type of hybrid orbital of  ${\mathbf{sp}}^{\mathbf{3}}$ except carbonyl which is ${\mathbf{sp}}^{\mathbf{2}}$  hybridized as an oxygen atom is attached with two lone pairs and one bond pair.

Hence, all the lone pairs of oxygen are not the same.