Question

Arrange the following from lowest to highest ionization energy: O, O2, O2-, and O2+. Please explain why. I'm thinking it has to do something with the bond energy. Sofar, I drew the MO model for each, but I don't know how that helps determine the ionization energy. Please help. Thank you

Answer 1

To thegiven all species , O₂ ^- has lower ionization energy than any other . Since it has containingmore number of electrons of its MO orbitals hence the effective nuclear charge was decreased .so it has low ionization energy. In the next two species O and O₂ , O₂ has lower ionization energybecause where the two electrons are paired up with other O atom . But O atom is more ionizationenergy . Finally O₂ ⁺ has high ionization energy than O₂ since O₂ ⁺ has high nuclearcharge .Therefore the order of ionization energy is to be as follows :O₂ ^- <O₂ <O₂ ⁺ < O .