So I was reading about the stability of elements based on Nuclear Binding Energy, and I saw that the 'Iron group' of elements were most tightly bound and hence most stable, and that is why the graph peaks there. Why do elements that come after Iron, which are less stable even exist? And if they do, why do they not constantly strive to achieve Iron-like stability?
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There are a couple of related questions:
- What elements can be created in the fusion process of different types of stars?
- What is the heaviest element possible produced in a supernova?
though surprisingly I can't find an exact duplicate (which probably just means I didn't look hard enough).
Iron is the most stable nucleus so in principle all other nuclei should fuse or fission to form iron, but the reaction is extremely slow because large kinetic barriers exist. If heavy nuclei are formed faster than they can decay then we end up with a signficiant concentration of the heavy nuclei.
In supernovae and stars heavy nuclei can be formed by the r-process and the s-process respectively. In normal stars the temperature is not high enough for the heavy nuclei to decay to iron at any significant rate (though they can be destroyed in other nuclear reactions). The temperature in supernovae may be high enough, but the high temperature lasts for too short a time. In either case the end result is a significant concentration of the heavy nuclei.
John Rennie
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