Chemical Bonding Result Question 22
22. Which one of the following molecules is expected to exhibit diamagnetic behaviour?
(2013 Main)
(a) $\mathrm{C} _2$
(b) $\mathrm{N} _2$
(c) $\mathrm{O} _2$
(d) $\mathrm{S} _2$
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Answer:
Correct Answer: 22. ( a,b )
Solution:
- $\mathrm{C}_2(6+6=12)=\sigma 1 s^2, \stackrel{*}{\sigma} 1 s^2, \sigma 2 s^2, \stackrel{*}{\sigma} 2 s^2, \pi 2 p_x^2 \approx \pi 2 p_y^2$
Since, all the electrons are paired, it is a diamagnetic species.
$ \mathrm{N}_2(7+7=14)=\sigma 1 s^2, \stackrel{*}{\sigma} 1 s^2, \sigma 2 s^2 \text {, }$
$ \stackrel{*}{\sigma} 2 s^2, \pi 2 p_x^2 \approx \pi 2 p_y^2, \sigma 2 p_z^2 $
It is also a diamagnetic species because of the absence of unpaired electrons.
$\mathrm{O}_2(8+8 =16) $
$\mathrm{S}_2 =\sigma 1 s^2, \stackrel{*}{\sigma} 1 s^2, \sigma 2 s^2, \stackrel{*}{\sigma} 2 s^2, $
$\sigma 2 p_z^2, \pi 2 p_x^2 \approx \pi 2 p_y^2 \stackrel{*}{\pi} 2 p_x^1 \approx \stackrel{*}{\pi} 2 p_y^1$
Due to the presence of two unpaired electrons, $\mathrm{O}_2$ and $\mathrm{S}_2$ both are paramagnetic molecules.
BETA
