Compare the stabilities of O2 , O2-,O22-

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Compare the stabilities of O2 , O2-,O22- .

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The stabilities of these can be best explained using Molecular orbital theory.

(i) Formation Oxygen molecule:
Electronic configuration of oxygen atom-1s² 2s² 2p⁴
Atomic orbitals of oxygen combine to form molecular orbitals.
BO = bonding orbitals
ABO = Anti-bonding orbitals
O2 :

Electronic configuration of Oxygen molecule =

Bond order in Oxygen molecule (O2)=
=½ [(Number of bonding electrons) – (number of anti-bonding electrons)]
= ½ [10 – 6]
= 2

O2- :

Bond order in Oxygen molecule (O2-)
=½ [(Number of bonding electrons) – (number of anti-bonding electrons)]
= ½ [10 – 7]
= 1½

O2-2 :

Bond order in Oxygen molecule (O2-2)
=½ [(Number of bonding electrons) – (number of anti-bonding electrons)]
= ½ [10 – 8]
= 1
With the increase in number of electrons in anti-bonding orbital the stability and bond order of the molecule decreases.
Thus Decreasing order of stability is: O2 > O2- > O2-2