Can some kind person please explain why He-4 is so high and Li-6 is so low on the graph of binding energy per nucleon. Copy of the graph here http://en.wikipedia.org/wiki/File:Binding_energy_curve_-_common_isotopes.svg" [Broken] It means that He-4 must be very stable right? Because binding energy is indicative of stability for reasons I can't quite recall at the moment.. but why is there such a spike as it goes up to He-4 and then down to Li-6 and Li-7 etc. I remember in something about astrophysics it said there were like resonances in C-12 for example that made it more stable than one might expect so is that the case for He-4? But otherwise why is it so stable, or is Lithium just very unstable? Argh, this stuff gets pretty confusing.. any help would be greatly appreciated.