Q11.48CP - Chemistry: Molecular Nature Of Matter And Change

Question

Tryptophan is one of the amino acids found in proteins:

           

(a) What is the hybridization of each of the numbered C, N, and O atoms? 

(b) How many sigma bonds are present in tryptophan? 

(c) Predict the bond angles at points a, b, and c.

Step-by-Step Solution

Answer

1. The hybridization of the numbered 2, 5, 6 C-atom has sp² hybridization numbered 4 C-atom has sp³ hybridized and 3 numbered O-atom has sp hybridized whereas 1 numbered N-atom sp² hybridized.
2. There are 28 sigma bonds in Tryptophan.
3. The bond angles at points (a) have 104⁰, (b) have 120^o and (c) have 120^o.     

Step 1: Bonding

Bonding may be defined as the force of attraction between two or more atoms to form a compound. The molecule can have the same atom and different atoms.

Hybridization may be defined as the mixing of the atomic orbital to form a hybrid orbital before bonding with another atomic orbital having a similar atomic orbital.

Step 2: VSPER Theory

The molecule is always bonded in a geometry in a three-dimensional structure using the hybrid orbital by the atoms. Due to the difference in the hybridization of the molecule the geometry of the molecule changes. 

 

The geometry of the molecule is:

sp hybridized molecule has linear shape molecule.

sp² hybridized molecule has trigonal planar geometry.

sp³ hybridized molecule has tetrahedral geometry.

sp³d hybridized molecule has trigonal bi-pyramidal geometry.

d²sp³ hybridized molecule has octahedral geometry.

Step 3: Sigma Bonding

Sigma bond is the bond between the molecules that is formed by the head-on-overlapping of the hybrid orbitals of the atoms. There are 28 sigma bonds in Tryptophan.

Step 4: Bond Angle

The bond angle may be defined as the angle between the bond pair of the two atoms. The angle depends upon the less repulsion between the bond pair-bond pair or bond pair – lone pair and lone pair – lone pair. The bond angles at points (a) hhave104⁰, (b) have 120^o and (c) have 120^o.