Two Protons Colliding- Stable Nuclei?

In summary, two protons can collide and become a stable nucleus through a process called proton-proton fusion, which is a key reaction in the sun. It requires high temperatures to overcome the electrostatic repulsion between the protons, and the strong nuclear force then binds them together to form stable nuclei. However, in the sun, this process is aided by quantum tunneling, which allows particles to cross barriers even if they do not have enough energy to do so in classical physics.
  • #1
axel65
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Hi, I'm new to this forum, so I'm sorry if I've posted this in he wrong catergory.

Anyway, I'm studying AS physics at the moment and my teacher was giving the class some lessons about the strong nuclear force and electrostatic repulsion of nucleons making the nucleus stable.

To get to the point, we started woundering whether two protons could collide with each other, providing they had sufficient energy, to become a stable nuclei- i.e. the protons could get close enough for the electrostatic repulsion and the strong nuclear force to balance. The physics teacher was unsure, and the chemistry teacher told me it wasn't possible, but didn't have time to give an explanation, so I still don't understand why. Can anybody help me out? :confused:

Thanks, Alex
 
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  • #2
Yes, they can.

It takes substantial energy - but it does happen, it's just difficult to achieve on earth.

However, the process of proton-proton fusion is one of the key reactions that takes place in the sun. 2 Hydrogen nuclei (protons) fuse to produce a deuterium nucleus (1 proton, 1 neutron) and a positron (positive electron). Subsequently, the deuterium nuclei can fuse with protons to form helium.

The electrostatic force provides substantial repulsion, hence the need for very high temperatures (about 15 million K). It is only at high temperatures that the KE of the protons is sufficient to overcome the electrostatic repulsion.

However, once you overcome electrostatics then the strong force will bind the 2 nucleons together - and produce a new nucleus. In the case of deuterium, and helium-3 and helium-4 the nuclei are stable. Tritium can also be produced, this is unstable and decays into helium-3.

There is a final catch - in that the temperatures of the sun aren't quite high enough to overcome the electrostatic repulsion between protons, so how can the reaction take place.

The solution is 'quantum tunneling' - A simple explanation: according to classical physics, if a particle doesn't has less energy than a barrier then the barrier acts like a brick wall - the particle can't cross it. In quantum mechanics, things are probability based - it's possible, for a particle to cross any barrier - the height of the barrier and the energy of the particle determine the probability that particle can cross. Occasionally, this means a particle can cross a barrier that is higher than its energy level - the particle appears to 'tunnel' through the barrier, instead of going over it.
 
  • #3


Hi Alex,

Welcome to the forum! Your question is a great one and it's good to see you thinking about the stability of nuclei. The short answer is no, two protons cannot collide and form a stable nucleus.

To understand why, we need to look at the forces involved. As you mentioned, the strong nuclear force is responsible for holding the nucleus together. This force is incredibly strong, but it has a very short range. This means that it only acts on particles that are very close together, like the protons and neutrons in the nucleus.

On the other hand, the electrostatic repulsion between two protons is caused by their positive charges. This force is much weaker than the strong nuclear force, but it has a longer range. This means that it can act over longer distances, which is why it can cause protons to repel each other even when they are not right next to each other.

When two protons collide, they will experience both the strong nuclear force and the electrostatic repulsion. As they get closer together, the strong nuclear force will become stronger and start to overcome the electrostatic repulsion. However, this only happens at very short distances, and before the two protons can get close enough for the strong nuclear force to balance out the electrostatic repulsion, they will repel each other and fly apart.

So, in order for two protons to form a stable nucleus, they would need to overcome the electrostatic repulsion and get close enough for the strong nuclear force to take over. This is possible in the case of larger nuclei, where there are many protons and neutrons working together to hold the nucleus together. But for just two protons, the electrostatic repulsion is too strong for the strong nuclear force to overcome.

I hope this helps to clarify things for you. Keep asking great questions and keep learning!
 

1. How do two protons collide?

Two protons can collide in a number of ways, such as in a particle accelerator or in the core of a star. In these collisions, the protons are accelerated to very high speeds and collide with each other, resulting in the merging of their nuclei.

2. What happens when two protons collide?

When two protons collide, they can either fuse together to form a new element or they can split apart into smaller particles. The outcome of the collision depends on the energy and angle at which the protons collide, as well as the stability of the nuclei involved.

3. Are stable nuclei formed in two protons collisions?

Yes, it is possible for stable nuclei to be formed in two protons collisions. However, the likelihood of this happening is dependent on the energy and angle at which the protons collide. In most cases, unstable nuclei are formed and then quickly decay into more stable forms.

4. Can two protons collide in nature?

Yes, two protons can collide in nature, particularly in the core of stars. In extreme conditions, such as in the core of the sun, protons are able to overcome their natural repulsion and come into close contact, resulting in nuclear fusion and the formation of stable nuclei.

5. What is the significance of studying two protons collisions in stable nuclei?

Studying two protons collisions and the resulting formation of stable nuclei allows scientists to better understand the fundamental forces and interactions of particles at a subatomic level. This knowledge can then be applied to other areas of physics and technology, such as nuclear energy and particle accelerators.

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