OK, in the meantime I did find out (after a thorough search on the net), that (O2)- is really paramagnetic, and that it really just has one unpaired electron. So it is paramagnetic, but less than O2. This is what I guessed, but now I know...
O2 has two unpaired electrons, therefore it's quite strong paramagnetism.
But what about (O2)-, the negatively charged O2 ion?
Am I right in assuming that due to the additional electron one unpaired electron will get together with it, so that overall it should still be paramagnetic, but...
There are the famous experiments, which show, how an Oxygen soap bubble gets attracted by a magnet due to it's paramagnetism. And how a Nitrogen bubble gets repelled by it (in air)But how does one calculate the attraction force of this pure Oxygen soap bubble in air due to a magnet.
I'm Sorry...