We are being asked why O2 is paramagnetic. To understand the magnetic properties of molecules, we must look at the distribution of electrons in the orbitals.
Paramagnetism refers to elements or ions that contain at least one unpaired electron, while diamagnetism refers to elements or ions with no unpaired electrons.
Molecular Orbital Theory allows us to predict the distribution of electrons within a molecule. This allows us to predict properties such as bond order, magnetism, and shape.
Why is O2 paramagnetic?