The bond energies increase in the order: O2^1 < O2 < O^-2< O2^-2 The number of unpaired electrons in O2^-1 and O2 is, respectively, 1 and 0. The bond order in O2^-and O2^-2 is, respectively, 2.5 and 1. Bond length increases with increasing bond order while bond energy decreases. The electron configuration of O2 is (?2s)2(?*2s)2(?2p)2(?2p)4(?*2p)1. The electron configuration of O2^-2 is (?2s)2(?*2s)2(?2p)2(?2p)4(?*2p)3.