Question

Pair of species among the following having same bond order as well as paramagnetic character will be:

• A. O$_2^-$, N$_2^-$
• B. O$_2^+$, N$_2^{2-}$
• C. O$_2^-$, N$_2^+$
• D. O$_2^+$, N$_2^-$

Hint:

Species with odd number of electrons are generally paramagnetic.

Answer 1

The Correct Option is D

To determine the pair of species which have both the same bond order and paramagnetic character, we need to understand the concepts of bond order and paramagnetism in molecular orbitals.

1. Understanding Bond Order:

Bond order helps in understanding the stability and strength of a bond in a molecule. It is calculated as:

\(\text{Bond Order} = \frac{\text{Number of bonding electrons} - \text{Number of antibonding electrons}}{2}\)

2. Paramagnetism:

A molecule is considered paramagnetic if it has one or more unpaired electrons in its molecular orbitals, which will result in an attraction to an external magnetic field.

3. Analysis of Given Options:

Let's calculate the bond order and magnetic character of each molecule:

• O₂^-: Total electrons = 17
• N₂^-: Total electrons = 13
• O₂⁺: Total electrons = 15
• N₂^2-: Total electrons = 14
• N₂⁺: Total electrons = 13

4. Calculating Bond Order and Magnetic Character:

O₂^-

• Bond Order = 1.5
• Paramagnetic (due to 1 unpaired electron)

N₂^-

• Bond Order = 2.5
• Paramagnetic (due to 1 unpaired electron)

O₂⁺

• Bond Order = 2.5
• Paramagnetic (due to 1 unpaired electron)

N₂^2-

• Bond Order = 2.0
• Diamagnetic (all electrons are paired)

N₂⁺

• Bond Order = 2.5
• Paramagnetic (due to 1 unpaired electron)

5. Conclusion

The pair O₂⁺ and N₂^- both possess a bond order of 2.5 and are paramagnetic due to one unpaired electron. Therefore, the correct answer is:

O₂⁺, N₂^-