I'm working with modern physics atm, and can't seem to wrap my head around the binding energies of some molecules.
At first, I thought that a negative binding energy = unstable molecule, and a positive binding energy = stable molecule.
But for example, Cobalt-60 is a radioactive (unstable) isotope and has a positive binding energy. But deuterium, which is a stable isotope of hydrogen, also has a positive binding energy. How is this possible? If both a stable and an unstable molecule can have a positive binding energy, what does it mean if a binding energy is negative/positive? What's the physical meaning? See calculations below:
$$Mass[27 protons] + Mass[33 neutrons] - Mass[Cobalt-60] = 27*1.00727647+33*1.00866501-59.9338222=0.5485...$$ $$Mass[1 proton] + Mass[1 neutron] - Mass[Deuterium] = 1*1.00727647+1*1.00866501-2.01410178=0.0018...$$