Understanding Dissociation Energy: O2+ vs O2

[gazepdapi1]

I am having some trouble understanding this concept. I get that the dissociation energy for N2 is much greater than N2+ because of the triple bond, which makes a stronger bond, and therefore it is harder to remove one bond, compared to N2+ where it is easier to remove the bond because of one less electron. My professor today though was saying that for oxygen, the dissociation energy of O2+ is higher than just O2. She explained why with orbital theory, but I was having trouble keeping up Can someone tell me why?

thanks

 

[eli64]

bond order = (#electrons in bonding orbitals - #electrons in antibonding orbitals)/2

In N2, bond order is (8-2)/2 = 3
In N2+, it is (7-2)/2 = 2.5 (lower, weaker bond)

Your textbook should have MO pictures for N2, O2

Do a similar calculation for O2, you should see why O2+ has a higher bond order

 

[gazepdapi1]

thank you for your help