N 2 has greater dissociation energy then N 2 + , where as O 2 has a lower dissociation energy than O 2 + because:

N2 has greater dissociation energy then N2+, where as O2 has a lower dissociation energy than O2+ because:    


2 Answers

Ashwin Sinha
520 Points
13 years ago

Dear Abhay,

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.

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Sudheesh Singanamalla
114 Points
13 years ago

Dear Abhay ,

write the molecular orbital formula for both O2+  and  O2

similarly do for N2 and N2+


according to aufbau principle , the energies of orbitals increases as 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p

so note if the electrons are completely are partially filled.

if electrons are partially filled, then it is easier to break so it has higher dissociation enthalpy and

if electrons are completely filled in the orbitals , then it is harder to break them , so they have lower dissociation enthalpy.


The Molecular Oribitals filling will be given in the Chemical Bonding Chapter of your NCERT class XI Textbook


Hope that helps,

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