Yes, the IP of O2 should be smaller than for O. This is easily predicted since the molecule has more electrons to counter the charge, and secondly, the charge can be distributed over two atoms instead of one. (And it's a general chemical principle that the more distributed a charge is, the more stable it is, i.o.w. less energy)Cool. So to calculate the first ionization for O2, would it be the same as the first ionization for O? I really don't think its that simple. There must be a different formula, right?