Which one of the following species will have maximum bond dissociation energy?

Which one of the following species will have maximum bond dissociation energy?
  1. $\mathrm{C}_{2}$
  2. $\mathrm{C}_{2}^{+}$
  3. $\mathrm{C}_{2}^{-}$
  4. $\mathrm{C}_{2}^{2-}$

Solution

$\mathrm{C}_{2}(8$ electrons $) ; \mathrm{KK}(\sigma 2 \mathrm{~s})^{2}(\sigma * 2 \mathrm{~s})^{2}\left(\pi * 2 \mathrm{p}_{x}ight)^{2}\left(\pi 2 \mathrm{p}_{y}ight)^{2} \quad$ Bond order $=(6-2) / 2=2$
$\mathrm{C}_{2}^{+}(7$ electrons $) ; \quad$ Bond order $=(5-2) / 2=1^{1} / 2$
$\mathrm{C}_{2}^{-}\left(9ight.$ electrons); $\quad \mathrm{KK}(\sigma 2 \mathrm{~s})^{2}(\sigma * 2 \mathrm{~s})^{2}\left(\pi 2 \mathrm{p}_{x}ight)^{2}\left(\pi 2 \mathrm{p}_{y}ight)^{2}\left(\sigma 2 \mathrm{p}_{y}ight)^{1} \quad$ Bond order $=(7-2) / 2=2^{1} / 2$
$\mathrm{C}_{2}^{2-}(10$ electrons $) ;$ Bond order $=(8-2) / 2=3$
Larger the bond order, larger the dissociation energy.

Asked in: JEE-TOPICTESTS-CHEMISTRY

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