Which of the following options represents the correct bond order?
Thinking process
To calcualte bond order, write the molecular orbital configuration of particular species and afterwards using the formula.
Bond order =`1/2` [Number of bonding `(N_(6))` - Number of anti-bonding electrons `(N_(a))`]

Options

A. `O_(2)^(-)gtO_(2)gtO_(2)^(+)`
B. `O_(2)^(-)ltO_(2)ltO_(2)^(+)`
C. `O_(2)^(-)gtO_(2)ltO_(2)^(+)`
D. `O_(2)^(-)ltO_(2)gtO_(2)^(+)`

Answer

B

Explanation

b) Electronic configuration of `O_(2)` (16 electrons)
`sigma1s^(2), sigma^(star)1s^(2), sigma^(star)2s^(2), sigma2p_(z)^(2), pi2p_(x)^(2)=pi2p_(y)^(2), pi^(star)2p_(x)^(1)=pi^(star)2p_(y)^(1)`
Bond order = `1/2(N_(b)-N_(a))=1/2(10-6)=2`
Electronic configuration of `O_(2)^(+)` (15 electrons)
`=sigma1s^(2), sigma^(star)1s^(2), sigma2s^(2), sigma^(star)2s^(2), sigma2p_(z)^(2), pi2p_(x)^(2)=pi2p_(y)^(2), pi^(star)2p_(x)^(1)=pi^(star)2p_(Y)^(0)`
Bond order `=1/2(N_(0)-N_(a)) = 1/2(10-5)=2.5`
Electronic configuration of `O_(2)^(-)` (17 electrons)
`=sigma1s^(2), sigma^(star)1s^(2), sigma2s^(2), sigma^(star)2s^(2), pi2p_(x)^(2)=pi2p_(Y)^(2), pi^(star)2p_(x)^(2)=pi^(star)2p_(y)^(1)`
Bond order =`1/2(N_(0)-N_(a)) = 1/2(10-7)=15`
Thus, the order of bond order is `O_(2)^(-) lt O_(2)ltO_(2)^(+)`