Now, the greater the binding energy, the less is the
total mass of a bound system, such as a nucleus Consequently, if nuclei
with less total binding energy transform to nuclei with greater binding
energy, there will be a net energy release This is what happens when a
heavy nucleus decays into two or more intermediate mass fragments
(fission) or when light nuclei fuse into a havier nucleus (fusion )
Exothermic chemical reactions underlie conventional energy sources
such as coal or petroleum