Will heating diatomic oxygen enough break the O=O bonds?
Yes, adding at least 495 kJ/mol of kinetic energy one way or another (thermally, photochemically by irradiation with photons of that energy, sonication, etc.) will cause $\ce{O2}$ to dissociate into monatomic oxygen. 

$$\ce{O2 -&gt;C[energy]\ 2O}$$