Ncert Exercises & Solutions

Diamagnetic species are those which contain no unpaired electrons. Which among the following are diamagnetic?

1. $N_{2}$

2. $N_{2}^{2 -}$

3. $O_{2}$

4. $O_{2}^{2 -}$

(a, d)

(a) Electronic configuration of

N_{2} = σ 1 s^{2}, σ * 1 s^{2}, σ 2 s^{2}, σ * 2 s^{2}, π 2 {p_{x}}^{2} \approx π 2 {p_{y}}^{2}, σ 2 {p_{z}}^{2}

It has no unpaired electron indicates diamagnetic species.

(b) Electronic configuration of

N_{2}^{2 -}

ion

= σ 1 s^{2}, σ * 1 s^{2}, σ 2 s^{2}, σ * 2 s^{2}, π 2 {p_{x}}^{2} \approx π 2 {p_{y}}^{2}, σ 2 {p_{z}}^{2}, π * 2 {p_{x}}^{1} \approx π * 2 {p_{y}}^{1}

It has two unpaired electrons, paramagnetic in nature.

O_{2} = σ 1 s^{2}, σ * 1 s^{2}, σ 2 s^{2}, σ * 2 s^{2}, σ 2 {p_{z}}^{2}, π 2 {p_{x}}^{2} \approx π 2 {p_{y}}^{2}, π * 2 {p_{x}}^{1} \approx π * 2 {p_{y}}^{1}

The presence of two unpaired electrons shows its paramagnetic nature.

(d) Electronic configuration of

O_{2}^{2 -}

ion

= σ 1 s^{2}, σ * 1 s^{2}, σ 2 s^{2}, σ 2 {p_{z}}^{2}, π 2 {p_{x}}^{2} \approx π 2 {p_{y}}^{2}, π * 2 {p_{x}}^{2} \approx π * 2 {p_{y}}^{2}

It contains no unpaired electron, therefore, it is diamagnetic in nature.