Question

The bond orders of $He _{2}^{+}$ and $He _{2}$ are respectively

• A. $\frac{1}{2}, 0$
• B. $0, \frac{1}{2}$
• C. 0,1
• D. 1,0

Answer 1

Answer: (A)

$He_{2}$ molecular orbital has electronic configuration as $\sigma l s^{2}, \sigma^{*} l s^{2}$

Bond order $=\frac{\text{(electrons in bonding molecular orbital) -

(electrons in antibonding molecular orbital)} }{2}$

For $He _{2}$ molecule bond order $=\frac{2-2}{2}=0$

Bond order is zero so, $He _{2}$ molecule does not exist.

In case of $He _{2}^{+}$ electronic configuration of molecular orbital is $\sigma l s^{2} \sigma^{*} 1 s^{1}$.

Bond order $=\frac{2-1}{2}=\frac{1}{2}$