Considering the potential energy of interacting particles, how does covalent bonding lower the energy of the system?
They would not bond if it was not lower energy. Like I said look at it from the other direction - it takes energy to pull them apart. An O2 molecule is actually smaller than an oxygen atom. It is a tight orbitals that fill the orbitals. Like hudling (spooning) from the cold. S likes to fill (2) and then P likes to fill up (6 I think). Actually 3 P orbital with 2 electrons per orbital as I recall. If has been a few years since I took chemistry.