Two questions about the binding energy chart?

[magdi_gamal]

Hello I'm a little confused about the binding energy chart and its relevance to nuclei stability.

1) why is nickel-62 nucleas more stable than iron-58 and iron-56 though they have higher binding energy?

2) Why is binding energy lower in nuclei with least number of nucleons?
correct me if I'm wrong, but my understanding is that the less nucleones there is the closer they'd be to the nucleus and therefore the strong nuclear force would be more dominant.
So wouldn't make sense that nuclei with the least number of nucleons to be harder to split apart, and so have a higher binding energy? I guess that's not the case seeing that they have the lowest binding energy in the chart, but why?

 

[magdi_gamal]

By the least number of nucleons elements, I meant H isotopes, HE, Li-6 Li-7...etc

 

[mfb]

In which respect is Ni62 "more stable"?
The iron nuclei might have more binding energy per nucleon, but what about the total binding energy?

2) Why is binding energy lower in nuclei with least number of nucleons?
correct me if I'm wrong, but my understanding is that the less nucleones there is the closer they'd be to the nucleus and therefore the strong nuclear force would be more dominant.

The nucleons are always in the nucleus, as the nucleus is made out of all nucleons. Small nuclei have a large surface relative to the volume, that lowers the binding energy.

 

[magdi_gamal]

In which respect is Ni62 "more stable"?

in the sense that its nucleones are more tightly bound, and not being able/not needing to decay I guess? I read somewhere on the Internet that it's the most stable nucleas.

The iron nuclei might have more binding energy per nucleon, but what about the total binding energy?

Oh, so the values presented in the binding energy chart are per nucleon NOT the overall binding energy?

The nucleons are always in the nucleus, as the nucleus is made out of all nucleons. Small nuclei have a large surface relative to the volume, that lowers the binding energy.

um, not sure I got this. So the nucleus is the entire area that holds the nucleones and not simply just the center point? and elements like Li, H, and helium basically have lower binding energy because they have a smaller nucleas?
okay, but despite their lower binding energy, they're still not even closely radioactive as elements such as Uranium. the reason being their low amount of nucleons right?
Thanks for your answer.

 

[Bill_K]

I read somewhere on the Internet that it's [Ni-62] the most stable nucleas

It says here that Ni-62 is the most tightly bound: (B.E. per nucleon) http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/nucbin2.html#c1

 

[mfb]

Oh, so the values presented in the binding energy chart are per nucleon NOT the overall binding energy?

Right.

um, not sure I got this. So the nucleus is the entire area that holds the nucleones and not simply just the center point? and elements like Li, H, and helium basically have lower binding energy because they have a smaller nucleas?

The nucleus is the whole volume where nucleons are present. This volume depends on the nucleus - in general, the volume is roughly proportional to the number of nucleons.

okay, but despite their lower binding energy, they're still not even closely radioactive as elements such as Uranium. the reason being their low amount of nucleons right?
Thanks for your answer.

Uranium is radioactive as emitting nucleons (-> alpha radiation) brings the remaining nucleus closer towards nickel/iron, towards larger binding energies per nucleon.
The corresponding process for small nuclei would be fusion, not decays. Fusion of small nuclei does indeed release a lot of energy, this is the energy source of stars.