My question is why aren't we seeing 4 neutrons sticking together

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In summary, the stability of the helium nucleus is due to the presence of two protons and two neutrons. While neutrons do exert a strong attractive nuclear force, they do not form nuclides on their own. This is because a nucleus must have at least one proton to have a nuclide, as it is the electrons that give atoms their chemical identity. However, in the presence of protons, neutrons can form stable nuclei. Neutron stars are also stable due to their immense gravity, which prevents neutrons from decaying. The unstable nature of neutrons prevents them from forming stable clumps on their own, and the electrostatic repulsion between protons further inhibits this process. The nuclei are held together by the
  • #1
bhthiang
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We all know that the helium nucleus is very stable because it consists of two protons and two neutrons.
My question is why aren't we seeing 4 neutrons sticking together forming an even more stable nuclide, since neutrons exert only the strong attractive nuclear force but not the repulsive Coulomb force?
 
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  • #2
It's not that neutrons don't stick together but that they don't form nuclides- you have to have at least one proton to have a nuclide: no protons, no electrons and so no atom! It is, after all, the electrons that give atoms their chemical identity.
 
  • #3
You do get clumps of nuetrons though.
Isn't that what a nuetron star is supposed to be?
 
  • #4
Originally posted by Ace-of-Spades
You do get clumps of nuetrons though.
Isn't that what a nuetron star is supposed to be?

Left by themselves, neutrons are unstable, with a half-life of 12 mins, and decay into a proton and electron.

The presence of already existing protons curtails this. When you have the right porportion, you get a stable nucleus. Otherwise, a nucleus with too many neutrons tends to undergo beta- decay (a neutron change to a proton and emits an electron.)

Nuclei with too few neutrons are unstable also, due to the fact that there aren't enough neutrons to overcome the electrostatic repulsion of the protons.

Neutron stars are stable because of the immense gravity due to their large mass. This squeezes the neutrons together so tightly that there isn't any "room" for the electrons which must be emitted in order for the neutrons to decay. (gravity overcomes the weak force)
 
  • #5
neutrons

Thanks for the fast response!
What I really want to find out is:

In their natural occurring way, why don't neutrons seek out one another and form stable clumps? Bear in mind that 2 neutrons and two protons do just that and form a very stable helium nuclide, although there is quite a bit of repulsive force between the two protons.

Could this have something to do with their quantum states being exclusive?
 
  • #6


Originally posted by bhthiang
In their natural occurring way, why don't neutrons seek out one another and form stable clumps? Bear in mind that 2 neutrons and two protons do just that and form a very stable helium nuclide, although there is quite a bit of repulsive force between the two protons.

Could this have something to do with their quantum states being exclusive?

As Janus pointed out, they are unstable on their own, hence it could be assumed that that unstability precludes stable particulate formation.

The manner of formation of the helium nucleous might be something you want to investigate, first.
 
  • #7


Originally posted by bhthiang
Thanks for the fast response!
What I really want to find out is:

In their natural occurring way, why don't neutrons seek out one another and form stable clumps? Bear in mind that 2 neutrons and two protons do just that and form a very stable helium nuclide, although there is quite a bit of repulsive force between the two protons.

Could this have something to do with their quantum states being exclusive?

Again, neutrons are unstable. If such a clump were to form, the neutrons would start to decay until enough protons were formed to create a stable nucleus.

It is the electrostatic repulsion of the protons with each other that would stop the process. After a certain point, the combined replusion of the protons overrides the weak interaction that causes neutron decay, preventing the formation of any more protons.
 
  • #8
The nuclei are held together by the constant exchange of particles (pions, or if you prefer, quarks) which cause the protons and neutrons to change into each other. Two protons by themselves can't support that, and neither can two neutrons. So you don't see all proton or all neutron nuclei. Except for Hydrogen of course, a single proton all by its lonesome.
 
  • #9
Originally posted by selfAdjoint
The nuclei are held together by the constant exchange of particles (pions, or if you prefer, quarks) which cause the protons and neutrons to change into each other. Two protons by themselves can't support that, and neither can two neutrons. So you don't see all proton or all neutron nuclei. Except for Hydrogen of course, a single proton all by its lonesome.

Do you have a reference for that statement? (the one in red)
 

1. Why aren't we seeing 4 neutrons sticking together?

This is a common question about nuclear physics and the behavior of subatomic particles. The answer lies in the strong nuclear force, which is responsible for holding the nucleus of an atom together. This force is very strong, but it has a limited range, so it only acts on particles that are very close together. When there are four neutrons in close proximity, the attractive force is not strong enough to overcome the repulsive forces between them, and they will not stick together.

2. Can four neutrons ever stick together?

Technically, yes, it is possible for four neutrons to stick together, but it is highly unlikely. This is because the strong nuclear force is a short-range force and the four neutrons would have to be extremely close together for it to overcome the repulsive forces between them. Additionally, neutrons are unstable and tend to decay into protons, making it even more difficult for four neutrons to stick together.

3. Are there any examples of four neutrons sticking together in nature?

No, there are no known examples of four neutrons sticking together in nature. As mentioned before, it is possible but highly unlikely due to the unstable nature of neutrons and the limitations of the strong nuclear force. In fact, even three neutrons sticking together is considered rare.

4. What happens when four neutrons are forced together?

If four neutrons are forced together, they will most likely undergo beta decay, where one or more of the neutrons will turn into a proton and release a beta particle. This is because the strong nuclear force is not strong enough to hold them together, and the repulsive forces between them will eventually cause them to break apart.

5. Could four neutrons be used to make a new element?

No, four neutrons cannot be used to make a new element. In order to create a new element, the nucleus must contain a specific number of protons, which determines its atomic number. Four neutrons cannot fulfill this requirement, and even if they could stick together, the resulting nucleus would not be a new element.

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