A covalent bond will be formed by the overlapping of atomic orbitals having single electron of opposite spin, according to the overlapping of atomic orbitals the covalent bond may be of two types :
(i) Sigma bond `(sigma) " " (ii) ` Pi bond `(pi)`
Sigma bond is stronger bond than the Pi-bond. If atomic orbitals overlap about the nuclear axis then sigma bond is formed but when atomic orbitals overlap sideway then Pi-bond is formed.
The strength of bonds formed by 2s-2s,2p-2p and 2p-2s overlap has the order :

Options

A. `s-s gt p-p gt p-s`
B. `s-s gt p-s gt p-p`
C. `p-p gt p-s gt s-s`
D. `p-p gt s-s gt p-s`

Answer

To determine the strength of bonds formed by the overlap of atomic orbitals (2s-2s, 2p-2p, and 2p-2s), we need to analyze the types of overlaps and their respective strengths. Here’s a step-by-step solution:

### Step 1: Understand the Types of Overlaps
- **2s-2s overlap (SS)**: This involves the overlap of two s orbitals. S orbitals are spherical in shape, which means their overlapping area is relatively smaller compared to p orbitals.
- **2p-2p overlap (PP)**: This involves the overlap of two p orbitals. P orbitals have a dumbbell shape, which allows for a larger area of overlap compared to s orbitals.
- **2p-2s overlap (PS)**: This involves the overlap of a p orbital with an s orbital. The area of overlap is greater than that of the s-s overlap but less than that of the p-p overlap.

### Step 2: Compare the Areas of Overlap
- The strength of a covalent bond is directly related to the area of overlap between the atomic orbitals.
- **PP (2p-2p)** has the largest area of overlap due to the shape of the p orbitals, which allows them to overlap effectively.
- **PS (2p-2s)** has a moderate area of overlap since it involves one p orbital and one s orbital.
- **SS (2s-2s)** has the smallest area of overlap because both orbitals are spherical and do not overlap as effectively as p orbitals.

### Step 3: Determine the Order of Bond Strength
Based on the areas of overlap:
1. **PP (2p-2p)**: Strongest bond due to the largest area of overlap.
2. **PS (2p-2s)**: Moderate bond strength due to a decent area of overlap.
3. **SS (2s-2s)**: Weakest bond due to the smallest area of overlap.

### Conclusion
The order of bond strength based on the overlap of atomic orbitals is:
**PP > PS > SS**