Which of the following bonds has the highest bond energy ?

Options

A. O - O
B. S - S
C. Se - Se
D. Te - Te

Answer

To determine which bond has the highest bond energy among the given options, we need to consider the factors that influence bond energy, such as atomic size, bond type, and the extent of orbital overlap. Let's analyze the bonds step by step.

### Step-by-Step Solution:

1. **Understanding Bond Energy**:
- Bond energy is the amount of energy required to break a bond between two atoms. Higher bond energy indicates a stronger bond.

2. **Identify the Bonds**:
- The bonds mentioned in the question are likely between elements such as O₂ (oxygen), S₂ (sulfur), Na₂ (sodium), and possibly another bond involving elements from group 16 (like tellurium).

3. **Consider Atomic Size**:
- As we move down a group in the periodic table, the atomic size increases. This affects the bond length and bond energy. Larger atoms have longer bond lengths, which generally leads to lower bond energies due to less effective overlap of atomic orbitals.

4. **Evaluate Overlap**:
- The strength of a bond is also influenced by the overlap of atomic orbitals. Greater overlap results in stronger bonds and higher bond energies.
- Oxygen (O) can form a double bond (O=O), which is strong due to effective overlap of p orbitals.
- Sulfur (S) can also form a bond (S=S), but it is larger than oxygen, leading to less effective overlap.

5. **Lone Pair Repulsion**:
- In O₂, there are lone pairs of electrons that can cause repulsion, which may weaken the bond slightly despite the strong overlap.
- In S₂, while there are also lone pairs, the larger size allows for better d-pi and p-pi overlap, leading to a stronger bond.

6. **Comparing Bond Energies**:
- O₂ has a high bond energy due to the double bond, but the lone pair repulsion slightly reduces it.
- S₂ has a good covalent bond with effective overlap, which can lead to higher bond energy compared to O₂.
- Na₂ and other larger bonds (like those involving tellurium) will have lower bond energies due to increased bond lengths and decreased overlap.

7. **Conclusion**:
- After comparing the bonds, S-S (sulfur-sulfur) bond is likely to have the highest bond energy due to effective orbital overlap and the nature of the bond formed.

### Final Answer:
The bond with the highest bond energy is **S-S (sulfur-sulfur)**.