Binding energy, fusion and fission

In summary, the conversation discusses the concept of binding energy and its relation to fission and fusion. The speaker has found their high school physics book to be inadequate in explaining these concepts and has done additional research. They have some questions and confusions, including the cause of fission and the role of neutrons in nucleus stability. The other person responds by explaining that fission can occur due to a collision or due to the nucleus becoming unstable, and that adding neutrons can excite the nucleus. The conversation also mentions spontaneous fissions and other ways in which a nucleus can become excited.
  • #1
Volta
8
0
Hi.

My high school physics book doesn't elaborate the idea of binding energy and how it's related to fissions and fuisions adequately in a way that made me have wrong thoughts about these ideas.
What i understand after doing some research is that:
- Binding energy is the energy that has to be given for nucleons to separate them from each other.

- Nucleons in stable nucleus have negative energy considering the energy of a free static nucleon to be the reference energy.

My questions and confusions:

- in fissions, does the nucleus divide because of the collision between the neutron and the heavy nucleus, or because the nucleus would become unstable after the mass number has increased.

- this question is related to the above one ; neutrons are supposed to be the main factor of nucleus stability because it contributes in the strong force. why does adding a new neutron or more to any nucleus without changing the number of protons, make the nucleus unstable?

- My book mentions that when alpha decay happens ,a decrease in mass turns into kinetic energy gained by the products. does it mean the decrease of mass because of the lost neutrons and protons or what?

- the process of losing mass for energy and vice versas in fissions and fuisions, shouldn't the mass for the neutrons shot out of the mass increase and that's it? where would energy come from?
 
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  • #2
Fission is possible because a nucleus may have negative binding energy relative separated nucleons, but there may exist smaller nuclei that have more (negative) bonding energy per nucleon. Thus, two smaller nuclei would have less total energy in their ground state then the on larger nucleus. More generally, nickel and iron have the highest binding energy per nucleon. Sufficiently smaller nuclei can exothermically fuse, and sufficiently larger nuclei can exothermically fission.
 
  • #3
Sorry for late reply, but i think your answer didn't address my questions.
 
  • #4
Volta said:
- in fissions, does the nucleus divide because of the collision between the neutron and the heavy nucleus, or because the nucleus would become unstable after the mass number has increased.
Both. Note that spontaneous fissions also exist. Nucleus has to release energy by fission, but it also has to get through barrier, whether by tunnelling or due to excitation.
Volta said:
- this question is related to the above one ; neutrons are supposed to be the main factor of nucleus stability because it contributes in the strong force. why does adding a new neutron or more to any nucleus without changing the number of protons, make the nucleus unstable?
Because it excites the nucleus.
Nucleus might also be excited by something else, like absorbing a photon or inelastic collision with a charged particle. But the nuclei often emit the energy by gamma without fission. If and after this has happened, spontaneous fission is still possible, but far rarer.
 

Related to Binding energy, fusion and fission

1. What is binding energy?

Binding energy is the amount of energy required to hold the nucleus of an atom together. It is a measure of the strength of the nuclear force that binds protons and neutrons together.

2. How is binding energy related to nuclear fusion?

In nuclear fusion, two or more smaller nuclei combine to form a larger nucleus. This process releases large amounts of energy, as the combined nucleus has a lower binding energy than the individual nuclei. The difference in binding energy is converted into energy according to Einstein's famous equation, E=mc^2.

3. What is the difference between fusion and fission?

Nuclear fusion is the process of combining smaller nuclei to form a larger nucleus, while nuclear fission is the process of splitting a larger nucleus into smaller nuclei. Both processes release energy, but the reactions and products are different.

4. How does binding energy affect the stability of an atom?

The higher the binding energy per nucleon (proton or neutron) in an atom, the more stable it is. This is because the strong nuclear force is able to overcome the repulsive electromagnetic force between protons, keeping the nucleus intact.

5. Can we harness the energy from nuclear fusion for practical use?

While nuclear fusion has the potential to provide a nearly limitless source of energy, it is currently not harnessed for practical use due to the high temperatures and pressures required to initiate and sustain the reaction. Scientists are working on developing fusion reactors, but it is still a complex and challenging process.

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