Question

Which of the following species have maximum number of unpaired electrons?

• A. O\(_2\)
• B. O\(_2^+\)
• C. O\(_2^-\)
• D. O\(_2^{2-}\)

Hint:

The number of unpaired electrons in a molecule can be determined by its molecular orbital configuration. O\(_2\) has the maximum number of unpaired electrons.

Answer 1

The Correct Option is A

Step 1: Electron configuration of O\(_2\).
The molecular orbital configuration of O\(_2\) is: \[ \sigma_{1s}^2 \sigma_{1s}^2 \sigma_{2s}^2 \sigma_{2s}^2 \pi_{2p_x}^2 \pi_{2p_y}^2 \pi_{2p_z}^1 \pi_{2p_z}^1 \] O\(_2\) has two unpaired electrons in the degenerate \( \pi_{2p_z} \) orbitals.
Step 2: Electron configuration of O\(_2^+\).
In O\(_2^+\), one electron is removed, leaving only one unpaired electron.
Step 3: Electron configuration of O\(_2^-\).
In O\(_2^-\), one additional electron is added, leading to two unpaired electrons.
Step 4: Electron configuration of O\(_2^{2-}\).
In O\(_2^{2-}\), two electrons are added, filling the \( \pi_{2p} \) orbitals and leaving no unpaired electrons.
Step 5: Conclusion.
O\(_2\) has the maximum number of unpaired electrons (two unpaired electrons).