Can we "fill" an atom with alpha particles?

In summary: An electric field will disappear inside a volume if there is no potential difference between the inside and the outside.
  • #1
Meson080
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The following passage has been extracted from the book "Modern's abc of Chemistry":
..Heisenberg in 1927, put forward a principle known as Heisenberg's uncertainty principle. It states that, it is not possible to measure simultaneously both the position and momentum (or velocity) of a microscopic particle, with absolute accuracy.

Lets fill an isolated atom by subatomic "Rutherford projectiles"-alpha particles. I hope it is possible. This doesn't seem to be a limit of our technology. Isn't it?

If we are successful in filling the an atom with alpha particles, we are decreasing the space for the electron and confining them to a least distance, isn't it?

Doesn't this experiment, give us belief of measuring simultaneously both the position and momentum with little greater (or even complete) certainty than what predicted by Heisenberg's principle? This doesn't seem to allow us to fill an atom with alpha particles.

So, can we fill an atom with alpha particles?

The above question is also posted in Physics stack exchange, interested folks can visit: Can we "fill" an atom with alpha particles?
 
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  • #2
First, you can't fill an atom with alpha particles. Alpha particles are the nuclei of helium-4 atoms and are have a charge of +2. They would repel each other and you'd never be able to contain them in such a small area.

In addition, it is a common misunderstanding that you can't measure both the momentum and position of a particle. The uncertainty principle is about measuring multiple particles that are prepared identically. In other words, if I shoot a million electrons through a slit, there is no way to know in advance what the momentum and position of any single electron will be with perfect accuracy for both. I can set up the experiment so that I will know either the position or the momentum of each electron to any arbitrary value prior to measurement, but this requires making the other value more uncertain. However, upon measuring each electron, I will find out both the position and momentum to whatever accuracy my experiment can see.
 
  • #3
Drakkith said:
First, you can't fill an atom with alpha particles. Alpha particles are the nuclei of helium-4 atoms and are have a charge of +2. They would repel each other and you'd never be able to contain them in such a small area.

Why can't we use the electric fields to confine the alpha particles into the atom?

In addition, it is a common misunderstanding that you can't measure both the momentum and position of a particle. The uncertainty principle is about measuring multiple particles that are prepared identically. In other words, if I shoot a million electrons through a slit, there is no way to know in advance what the momentum and position of any single electron will be with perfect accuracy for both. I can set up the experiment so that I will know either the position or the momentum of each electron to any arbitrary value prior to measurement, but this requires making the other value more uncertain.

I didn't find any such explanation in any of my books, can you suggest me a book or a link to read about the uncertainty principle?

However, upon measuring each electron, I will find out both the position and momentum to whatever accuracy my experiment can see.

Isn't this in contradiction with the statement of the Heisenberg's Uncertainty Principle, I provided in the first post?
 
  • #4
Meson080 said:
Isn't this in contradiction with the statement of the Heisenberg's Uncertainty Principle, I provided in the first post?

Yes, because as Drakkith explained, what you posted was not what the HUP actually says. It is better understood now than it was then. This has been a subject of serious contention on this forum. There are still those who believe in the theoretical limit of measuring a single quantum object but most understand it to be as Drakkith says, a statistical thing. You set up an experiment to produce a particle and measure the results, then you run EXACTLY the same experiment and measure the results of that run. You don't get the same results.
 
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  • #5
Meson080 said:
Why can't we use the electric fields to confine the alpha particles into the atom?

Imagine you have a hollow metal sphere with a positive charged particle inside. You want to keep it right in the middle so you charge the entire sphere with a positive charge. Unfortunately, this leads to the electric field disappearing inside since there's no potential difference anywhere inside the sphere. In other words, the charged particle will experience no force and will act as though the sphere is uncharged. You simply cannot contain charges inside a volume of space by using repulsive electric forces.


I didn't find any such explanation in any of my books, can you suggest me a book or a link to read about the uncertainty principle?

After searching for a reference, I've come to the conclusion that I may not know what I'm talking about. I'll let someone else with more knowledge handle this.

Edit: I see Phinds has the same idea I do about this. It's honestly something that I've seen explained here on PF several times, but I can't be certain it's correct. Hopefully someone can clear this up.
 
  • #6
Meson080 said:
Lets fill an isolated atom by subatomic "Rutherford projectiles"-alpha particles. I hope it is possible. This doesn't seem to be a limit of our technology. Isn't it?

Actually it is the limit of our technology. You are talking about nuclear fusion. It is thought this might be possible to achieve in the laboratory in a practical manner in the next 50 years or so (successes so far have been limited in their applications). I believe it is considered a cutting edge research topic in the field of plasma physics, at least.

As far as I know the only time that happens in nature is inside the core of red supergiant class stars (the biggest stars) near the end of that phase of stellar evolution. To fuse, you actually have to overcome the EM repulsion until the attractive strong force takes over (or there can be some tunneling effects as well). 100 million Kelvins is the order of magnitude temperature we are talking for that to occur. (edit: not to mention astronomical amounts of gravitational acceleration)

The particular reaction of alpha particles fusing together is called the triple-alpha process. The result is beryllium (from 2 alpha combo) and carbon (from beryllium and yet another alpha), and like 7 million electron volts per reaction. The energy comes from the fact that when nuclei form, the sum of the parts is actually less that the resulting nuclei. It would be like measuring the mass of all the parts of a bicycle, summing them together, and then comparing that with the mass of the assembled bicycle and getting a different answer. Weird, huh?
 
  • #7
Mishima, I was under the impression the OP was talking about shoving a bunch of alpha particles inside an atom without fusing them together inside the nucleus.

What say you, Meson?
 
  • #8
Sorry if I misread, I have no idea what you are talking about if that's the case. How can a positively charged particle be bound to a nucleus without strong force interactions?
 
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  • #9
mishima said:
Sorry if I misread, I have no idea what you are talking about if that's the case. How can a positively charged particle be bound to a nucleus without strong force interactions?

It can't.
 
  • #10
Drakkith said:
It can't.

:devil::devil::devil:I am going to the class now. Wait I will be back!:biggrin:
 
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  • #11
Even if you *could* fuse enough nucleons to make a nucleus with a size comparable to the atom size, this would be a nucleus with a ridiculously high A, about 4e22 (nucleons are tiny!). Such an element would be highly unstable to the degree of not being possible to create.

Regarding the HUP: It is impossible to know the position and momentum of a particle at the same time. If you measure x first, them p, then x again, you will get different results in your x measurements. (You can also do the corresponding thing with any two non-commuting operators, such as the spin of a particle in two different directions.)
 
  • #12
Drakkith said:
Imagine you have a hollow metal sphere with a positive charged particle inside. You want to keep it right in the middle so you charge the entire sphere with a positive charge. Unfortunately, this leads to the electric field disappearing inside since there's no potential difference anywhere inside the sphere. In other words, the charged particle will experience no force and will act as though the sphere is uncharged. You simply cannot contain charges inside a volume of space by using repulsive electric forces.

But, this analogy doesn't scale properly/match properly with our experiment of confining alpha particles into the atom.
 
  • #13
Orodruin said:
Even if you *could* fuse enough nucleons to make a nucleus with a size comparable to the atom size, this would be a nucleus with a ridiculously high A, about 4e22 (nucleons are tiny!). Such an element would be highly unstable to the degree of not being possible to create.

Anyhow, I didn't want the charged atom to be stable. I just wanted it to be fused for a moment, in your words.
 
  • #14
Meson080 said:
But, this analogy doesn't scale properly/match properly with our experiment of confining alpha particles into the atom.
You missed the point, which is that the field will not point in. You cannot even keep a single charge in the middle of the sphere, let alone fill the sphere with charges. The analogy is an even simpler task than what you want, but even that simple task cannot be accomplished.
 
  • #15
Meson080 said:
Anyhow, I didn't want the charged atom to be stable. I just wanted it to be fused for a moment, in your words.

The real problem is that you will never be able to do that either. There is simply not going to be a bound state with that many nucleons.
 
  • #16
Meson080 said:
If we are successful in filling the an atom with alpha particles, we are decreasing the space for the electron and confining them to a least distance, isn't it?

Doesn't this experiment, give us belief of measuring simultaneously both the position and momentum with little greater (or even complete) certainty than what predicted by Heisenberg's principle?
This is not correct. The wavefunctions of the electrons are not excluded from the nucleus. Even if the nucleus took up a large volume, the space for the electrons is not decreased.
 
  • #17
Orodruin said:
The real problem is that you will never be able to do that either. There is simply not going to be a bound state with that many nucleons.

What about dipping the atoms into the sea of alpha particles?
 
  • #18
DaleSpam said:
This is not correct. The wavefunctions of the electrons are not excluded from the nucleus. Even if the nucleus took up a large volume, the space for the electrons is not decreased.

Can you elaborate?

If the atom gets filled by alpha particles, for the layman like me, the space for the electron should decrease. Or else electron should have got different space, does the electron buys different land around nucleus?
 
  • #19
Meson080 said:
Can you elaborate?

If the atom gets filled by alpha particles, for the layman like me, the space for the electron should decrease. Or else electron should have got different space, does the electron buys different land around nucleus?
Unfortunately, nature didn't ask for the opinions of laymen when she picked the rules, but don't feel too bad, she didn't ask for the opinions of experts either.

Look at these images of electron orbitals for hydrogen:
http://en.wikipedia.org/wiki/Hydrogen_atom#Visualizing_the_hydrogen_electron_orbitals

The bright spots are regions where the electron is likely to be, and the dark spots are regions where the electron is unlikely to be. Note that, for the s orbitals, the brightest spot is right in the middle, on top of the nucleus. In other words, the s electron is more likely to be in the nucleus than in any other spot of similar volume.

Weird, but that is how it is. Increasing the number of nucleons doesn't change this at all, although increasing the number of electrons changes the wavefunctions quantitatively, but not qualitatively.
 
  • #20
Meson080 said:
What about dipping the atoms into the sea of alpha particles?

There is no such thing. Alpha particles are highly charged particles that are emitted by radioactive decay and immediately steal electrons from whatever material they happen to come to a stop in. You will not find a "sea" of alpha particles nor could you even make one.
 
  • #21
DaleSpam said:
Unfortunately, nature didn't ask for the opinions of laymen when she picked the rules, but don't feel too bad, she didn't ask for the opinions of experts either.

Look at these images of electron orbitals for hydrogen:
http://en.wikipedia.org/wiki/Hydrogen_atom#Visualizing_the_hydrogen_electron_orbitals

The bright spots are regions where the electron is likely to be, and the dark spots are regions where the electron is unlikely to be. Note that, for the s orbitals, the brightest spot is right in the middle, on top of the nucleus. In other words, the s electron is more likely to be in the nucleus than in any other spot of similar volume.

Weird, but that is how it is. Increasing the number of nucleons doesn't change this at all, although increasing the number of electrons changes the wavefunctions quantitatively, but not qualitatively.

How could the electrons have the probability of having the position at the place where there are already quarks? Did electron learn the magic of entering the body of quarks? :biggrin:
 
  • #22
Drakkith said:
There is no such thing. Alpha particles are highly charged particles that are emitted by radioactive decay and immediately steal electrons from whatever material they happen to come to a stop in. You will not find a "sea" of alpha particles nor could you even make one.

Not even in "high security" condition?
 
  • #23
You seem to be working under the assumption that elementary particles are small balls that have a non-zero size. This is not the case in quantum mechanics (or classical particle theory either for that matter).
 
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  • #24
Meson080 said:
How could the electrons have the probability of having the position at the place where there are already quarks? Did electron learn the magic of entering the body of quarks? :biggrin:

Elementary particles are considered to be "point like" in that they have no size. Of course, this is a very simplified version of the truth, which is far more complicated in quantum physics and depends on how you define the size of a particle, of which there is no single answer.

Meson080 said:
Not even in "high security" condition?

I don't know what this means.
 
  • #25
Meson080 said:
Did electron learn the magic of entering the body of quarks? :biggrin:
Yes.

More explicitly, quarks don't have a definite location any more than the electrons, and even if they did the Pauli exclusion principle only applies to identical fermions and would therefore not prevent colocation of a quark and an electron.

You are thinking purely classically, your classical assumptions are simply wrong at the quantum level.
 
  • #26
Orodruin said:
You seem to be working under the assumption that elementary particles are small balls that have a non-zero size. This is not the case in quantum mechanics (or classical particle theory either for that matter).

Did you mean that elementary particles have zero size?
 
  • #27
Drakkith said:
I don't know what this means.

"High Security" condition = Sophisticated condition.
 
  • #28
Meson080 said:
Did electron learn the magic of entering the body of quarks? :biggrin:

DaleSpam said:
Yes.

Interesting, I will be back with the words within hours.
 
  • #29
Meson080 said:
Did you mean that elementary particles have zero size?

Yes, but the concept of "size" is poorly defined at the quantum level due to the unique nature of quantum sized objects and the fact that they obey both wave and particle rules. I know there are a few threads around PF on the subject. I'd recommend searching for them.

Meson080 said:
"High Security" condition = Sophisticated condition.

I still don't understand what this means in the context of my earlier explanation.
 
  • #30
Meson080 said:
How could the electrons have the probability of having the position at the place where there are already quarks? Did electron learn the magic of entering the body of quarks? :biggrin:

DaleSpam said:
Yes.

Feynman said:
You know, of course, that atoms are made with positive protons in the nucleus and with electrons outside. You may ask: "If this electrical force is so terrific, why don't the protons and electrons just get on top of each other? If they want to be in an intimate mixture, why isn't it still more intimate?" The answer has to do with quantum effects. If we try to confine our electrons in a region that is very close to the protons, then according to the uncertainty principle they must have some mean square momentum which is larger the more we try to confine them. It is this motion, require by the laws of quantum mechanics, that keeps the electrical attraction from bringing the charges any closer.

I am really perplexed, Feynman says electrons can't get on top of protons, Dalespam says electrons have learned the magic of entering the body of protons (which consists of quarks). Whom shall I believe? :confused:

[The Feynman's quote has been extracted from Feynman's Lectures on Physics-Vol ll]
 
  • #31
Meson080 said:
Did you mean that elementary particles have zero size?

Drakkith said:
Yes, but the concept of "size" is poorly defined at the quantum level due to the unique nature of quantum sized objects and the fact that they obey both wave and particle rules.

I don't think we should think/talk about anything which is defined poorly. Even it is not sensible to say zero or non-zero "size".
 
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  • #32
Meson080 said:
What about dipping the atoms into the sea of alpha particles?

Drakkith said:
There is no such thing. Alpha particles are highly charged particles that are emitted by radioactive decay and immediately steal electrons from whatever material they happen to come to a stop in. You will not find a "sea" of alpha particles nor could you even make one.

Meson080 said:
Not even in "high security" condition?

Drakkith said:
I don't know what this means.

"High Security" condition = Sophisticated condition = ICU condition = Condition of forming the sea of alpha particles without bringing any conflicts (e.g the conflicts you mentioned).
 
  • #33
Meson080 said:
I am really perplexed, Feynman says electrons can't get on top of protons, Dalespam says electrons have learned the magic of entering the body of protons (which consists of quarks). Whom shall I believe? :confused:

[The Feynman's quote has been extracted from Feynman's Lectures on Physics-Vol ll]
We are both correct. Feynman is answering a different question than what you are asking, so you shouldn't be surprised that the answers are different.

In any case, this whole line of discussion was an attempt to avoid the uncertainty principle, which is the basis of Feynman's comment. So either way, even if you think there is some conflict in our two statements, you still wind up with the uncertainty principle.
 
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  • #34
Meson080 said:
"High Security" condition = Sophisticated condition = ICU condition = Condition of forming the sea of alpha particles without bringing any conflicts (e.g the conflicts you mentioned).

I will not answer any "what if" questions that require us to handwave the laws of physics aside. It's pointless and will most likely lead to further confusion.
 
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  • #35
DaleSpam said:
Feynman is answering a different question than what you are asking, so you shouldn't be surprised that the answers are different.
To be a little more explicit, Feynman's comments were answering the question "why is the electron not constrained to be inside the proton?" The answer is that the uncertainty principle for such a tightly constrained position for the electron would have a very high mean momentum and therefore a high mean KE.

My comments were answering the question "why is the electron not constrained to be outside of the proton?" The answer is that the Pauli exclusion principle only constrains identical fermions, so it does not constrain an electron and a proton.

The electron is not constrained to be inside the proton (Feynman) and it is also not constrained to be outside the proton (me). The two comments are perfectly compatible.
 
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<h2>1. Can we actually "fill" an atom with alpha particles?</h2><p>Technically, no. The concept of "filling" an atom with alpha particles suggests that the atom is completely filled with these particles, which is not possible. However, we can say that an atom is "filled" with alpha particles if the number of alpha particles present in the atom's nucleus is at its maximum capacity.</p><h2>2. How many alpha particles can an atom hold?</h2><p>The maximum number of alpha particles that an atom can hold depends on the specific atom. Each type of atom has a different number of protons and neutrons in its nucleus, which determines its capacity for alpha particles. Generally, larger atoms have a higher capacity for alpha particles than smaller atoms.</p><h2>3. How do alpha particles affect the stability of an atom?</h2><p>Alpha particles can actually contribute to the stability of an atom. When an atom has an excess of protons, it can become unstable. Alpha particles, which contain two protons and two neutrons, can be emitted from the nucleus of an unstable atom, reducing its number of protons and making it more stable.</p><h2>4. Can we artificially add alpha particles to an atom?</h2><p>Yes, it is possible to artificially add alpha particles to an atom through a process called nuclear transmutation. This involves bombarding an atom with high-energy particles, such as protons or neutrons, which can cause the atom to absorb the particles and become a different element.</p><h2>5. What are some practical applications of filling atoms with alpha particles?</h2><p>Filling atoms with alpha particles is primarily used in nuclear reactions and research. It can also be used in medical treatments, such as in radiation therapy for cancer. Additionally, the study of alpha particles and their interactions with atoms can provide valuable insights into the structure and behavior of matter at a subatomic level.</p>

1. Can we actually "fill" an atom with alpha particles?

Technically, no. The concept of "filling" an atom with alpha particles suggests that the atom is completely filled with these particles, which is not possible. However, we can say that an atom is "filled" with alpha particles if the number of alpha particles present in the atom's nucleus is at its maximum capacity.

2. How many alpha particles can an atom hold?

The maximum number of alpha particles that an atom can hold depends on the specific atom. Each type of atom has a different number of protons and neutrons in its nucleus, which determines its capacity for alpha particles. Generally, larger atoms have a higher capacity for alpha particles than smaller atoms.

3. How do alpha particles affect the stability of an atom?

Alpha particles can actually contribute to the stability of an atom. When an atom has an excess of protons, it can become unstable. Alpha particles, which contain two protons and two neutrons, can be emitted from the nucleus of an unstable atom, reducing its number of protons and making it more stable.

4. Can we artificially add alpha particles to an atom?

Yes, it is possible to artificially add alpha particles to an atom through a process called nuclear transmutation. This involves bombarding an atom with high-energy particles, such as protons or neutrons, which can cause the atom to absorb the particles and become a different element.

5. What are some practical applications of filling atoms with alpha particles?

Filling atoms with alpha particles is primarily used in nuclear reactions and research. It can also be used in medical treatments, such as in radiation therapy for cancer. Additionally, the study of alpha particles and their interactions with atoms can provide valuable insights into the structure and behavior of matter at a subatomic level.

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