radioboy
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Why Gold (Au-197) doesn't decay with alpha particle?
What conditions are neccessary for some element to decay? I've been watching these so-called q-values (energies) for each isotope and found values for
neutron separation energy, proton separation energy, energy of beta and alpha and mixed decays... Shouldn't some element decay if it has positive
energy for something (as Au-197) has for alpha decay? Here is link: nrv.jinr.ru/nrv/webnrv/map/nucleus.php?q=Au197
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Joe Skulan
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All nuclei heavier than 56Fe (except 62Ni) are thermodynamically unstable and might be expected to decay given long enough, just as, given long
enough, all lighter nuclei might be expected to fuse into 56Fe or 62Ni. But just as in regular chemistry in nuclear chemistry there are kinetic
inhibitions to what is thermodynamically favored that control whether a process actually will happen, and at what rate. Kinetic effects tend to be
idiosyncratic and difficult to model. There is no master theory of radioactive decay that allows us to accurately predict the half lives of nuclei.
That needs to be worked out empirically. Alpha decay is especially problematic. Alpha decay is not possible under classical mechanics because it is
impossible for an alpha particle to get the kinetic energy it needs to overcome the binding forces of the nucleus and leave it. It's like trying to
get out of a glass phone booth with a baseball bat-- you don't have enough room to swing hard enough to break the glass. Alpha decay requires quantum
tunneling.
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