# Analysis of Fusion & Fission by Binding Energy

• B
• A M
In summary, the direction of fission and fusion reactions is opposite depending on the atomic mass of the reactants. For lighter elements, the fusion reaction is exothermic, while for heavier elements, the fission reaction is endothermic.
A M
TL;DR Summary
I wanted to write a student article specially for those who don't have a background in nuclear physics. I've been suggested to share my basic understanding & ask if they're correct.
I would be grateful if anyone could explain where my mistakes are:
(Please note that diagrams are designed just to give a simple imagination of the article & make it more understandable; they do NOT correspond precise information.)
In fusion reactions, lighter nuclei are combined into heavier ones (atomic mass increases); so the direction is from left to right (shown on the diagram). Therefore, in the fusion of 'light elements' the total final binding energy is higher (the related arrow points upward); so ##B_2-B_1>0## and energy is released. But for the fusion of 'heavy elements', the reverse is true, so ##B_2-B_1<0## and energy is needed.
In fission processes, heavier nuclei split to lighter ones (atomic mass decreases); so the direction is from right to left. Thus, in the fission of 'light elements' total final binding energy is lower (the arrow points downward); so ##B_2-B_1<0## and energy is utilized. But according to the arrow pointing up, the fission of 'heavy elements' is exothermic.

Last edited:
At least for me, when I first looked at the top graph, my thought was "That's wrong" because I've never really seen arrows pointing the same way on a BE graph like that before. (after looking at the graphs carefully and reading your words, they look accurate to me now, but are still confusing on first glance)

More usually, I'm used to seeing the traditional single BE graph that shows how Fusion and Fission reactions differ, and shows that Fe is the very stable element in the middle of those two regions of the graph. Here is a simple version that I found quickly with Google Images:

https://aggle.blogspot.com/2011/03/fission-and-fusion.html

I'm not sure there is a lot of value in talking about "endothermic" nuclear reactions going the opposite directions on the BE graph. Trying to add that into the discussion, especially with students who have not learned a lot yet about nuclear reactions, may not have as much value as just making them familiar with the exothermic nuclear reactions.

My two cents...

This is almost the last part of my article; before which I've already analyzed BE/A curve and explained exothermic and endothermic processes and how to calculate released/utilizes energy by the difference in final and initial total binding energies (##B_2-B_1##). Then I explained simple definitions of fission and fusion.

The only 'missing' fact was that why they don't always release energy, i.e. why "light nuclei are more fusible and heavy nuclei are more fissionable".
I thought the most understandable explanation would be to elucidate the reason on the graph I've just analyzed and compare them by indicating two arrows in each diagram.

(It is essential to to explain why elements heavier than iron can't be created in star evolution nucleosynthesis or why [α, SF, CD] modes of radioactive decay can't occur in naturally occurring light nuclei.)

## 1. What is fusion and fission?

Fusion is the process of combining two or more atomic nuclei to form a heavier nucleus, while fission is the process of splitting a heavy nucleus into two or more lighter nuclei.

## 2. How is binding energy related to fusion and fission?

Binding energy is the energy released or required to hold the nucleus of an atom together. In fusion, the binding energy is released when lighter nuclei combine to form a heavier nucleus, while in fission, the binding energy is released when a heavy nucleus splits into lighter nuclei.

## 3. What is the significance of binding energy in nuclear reactions?

The amount of binding energy released in a nuclear reaction determines the stability and energy output of the reaction. Higher binding energy results in a more stable nucleus and a larger release of energy.

## 4. How is binding energy calculated in fusion and fission reactions?

The binding energy of a nucleus can be calculated using the famous equation, E=mc², where E is the binding energy, m is the mass defect (difference between the mass of the individual nucleons and the mass of the nucleus), and c is the speed of light. The binding energy per nucleon can also be calculated by dividing the total binding energy by the number of nucleons in the nucleus.

## 5. What are the potential applications of fusion and fission reactions?

Fusion reactions have the potential to provide a nearly unlimited source of clean energy, while fission reactions are currently used in nuclear power plants to generate electricity. Both reactions also have important applications in nuclear weapons and in medical treatments such as cancer therapy.

• High Energy, Nuclear, Particle Physics
Replies
1
Views
1K
• High Energy, Nuclear, Particle Physics
Replies
11
Views
1K
• High Energy, Nuclear, Particle Physics
Replies
5
Views
2K
• High Energy, Nuclear, Particle Physics
Replies
4
Views
1K
• High Energy, Nuclear, Particle Physics
Replies
1
Views
1K
• High Energy, Nuclear, Particle Physics
Replies
3
Views
2K
• High Energy, Nuclear, Particle Physics
Replies
4
Views
5K
• High Energy, Nuclear, Particle Physics
Replies
1
Views
2K
• High Energy, Nuclear, Particle Physics
Replies
5
Views
917
• High Energy, Nuclear, Particle Physics
Replies
2
Views
9K