Question

The number of species among the following, having bond order of three is ............. \[ \text{N}_2, \text{F}_2, \text{NO}^+, \text{O}_2^-, \text{N}_2^+, \text{CO}, \text{O}_2, \text{O}_2^{2-} \]

Hint:

For bond order, use molecular orbital theory to determine the number of bonding and anti-bonding electrons, then apply the bond order formula.

Answer 1

To determine the bond order, we use the molecular orbital theory, where the bond order is given by: \[ \text{Bond order} = \frac{1}{2} \left( \text{number of electrons in bonding orbitals} - \text{number of electrons in anti-bonding orbitals} \right) \] We calculate the bond order for each species:
- N\(_2\): Bond order = 3 (from molecular orbital theory).
- F\(_2\): Bond order = 1 (since the bonding electrons fill the orbitals and anti-bonding orbitals reduce the bond order).
- NO\(^+\): Bond order = 3 (because of the removal of one electron).
- O\(_2^-\): Bond order = 2 (adding one extra electron).
- N\(_2^+\): Bond order = 2 (loss of one electron reduces the bond order).
- CO: Bond order = 3.
- O\(_2\): Bond order = 2.
- O\(_2^{2-}\): Bond order = 1.
The species with a bond order of 3 are: N\(_2\), NO\(^+\), CO.
Final Answer: \[ \boxed{3} \]