Write the MO configuration of the following species-

O2 , O2+ , O2- , O22-

Arrange them in order of their decreasing stabilities?

The electronic configuration for O is given as:

  • O-atom : 1s 2s 2p 4
    The molecular orbital configuration for O2 molecule can be given as:

  • O2 : (σ1s)2 (σ*1s)(σ2s)2 (σ*2s)2 (σ2pz )2 (π2px2 = straight pi2py2)(π*2px1=π*2py1)

  • Bond order 
    O2+ will form by removal of 1 electron from O2.The electron will be removed from π*2px or π*2py orbital.

    Bond order in O2 = 10-5/2= 2.5
    Bond order in O2 - = 10-7/2 = 1.5
     Bond order in O22- = 10-8/2 = 1


    So Order of bond order in all four species will be in order : O22-< O2<O2 < O2+

    Maximum the bond order, maximum will be stability.
    So the stability order of given species will be O2+ > O> O2 - >O22-

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