Need some confermation on electron spin meaning?

[thankz]

I just need a simple confermation, when the outermost shells of an atom have unpaired electrons is it the pairing of electrons between two different atoms say oxygen and two hydrogens that causes them to bond together?

I keep going back to counting subshells and their spins? my mind went somewhere?

 

[thankz]

nevermind I think I know the answer.