Why doesn't the Electron crash into the proton in an H atom?

[ZapperZ]

maybe its more a question of how to interpret quantum mechanics.

One certainly can't "interpret" QM by wanting to add to it what it doesn't have, like an "extra force". That's not an interpretation. That's a mistake.

I've written elsewhere on why QM is SO difficult. Maybe people should start reading that first before wanting to "interpret" it. One can't try to interpret something based on ignorance. That's a recipe not only for disaster, but for crackpottery.

Zz.

 

[edguy99]

It's not about "feelings". It's about calculations. Heisenberg uncertainty makes a very specific prediction: \Delta x \Delta p \geq \hbar/2. 0.5 A and 0.1 eV also violates this.

If you want to know if any other pair of \Delta x and \Delta p work, you can calculate them yourself. Note that a lower bound on E corresponds to a lower bound on p.

You shouldn't be too surprised that \Delta x of order an Angstrom works out to \Delta E of order 10 eV.

I am surprised by that. A hydrogen molecule is certainly less then one angstrom and there seem to be a pretty good chance that there is an electron somewhere in there with less they 10ev of energy. Is the hydrogen molecule in and of itself a violation of the uncertainty principle?

 

[Vanadium 50]

I am surprised by that. A hydrogen molecule is certainly less then one angstrom and there seem to be a pretty good chance that there is an electron somewhere in there with less they 10ev of energy. Is the hydrogen molecule in and of itself a violation of the uncertainty principle?

Seem...

...pretty good chance...

...somewhere in there...

I don't know what else to say but "do the calculations". This is a quantitative science. Write down a well-defined, quantitative question, do the QM calculation, and look at the answer.

 

[edguy99]

... and all of this is meaningful in what way? What useful information do you get out of this that has any resemblance to reality?

For your information, I could come up with a gazillion toy-model that would blow you away. Want to see my toy-model that initiates a vacuum breakdown? It is as useful as yours.

Zz.

To me it is meaningful in a goal to model or simulate processes such as hydration and polymerization where you must track things over time. The model of electrons stuck inside a shell by an amount equal to their ionization energy, together with the normal coulomb force pushing protons apart, leads to the most common forms of hydrogen that are easy to draw and conceptualize (is there a spell checker in this application?).

 

[malawi_glenn]

How does a molecule have a size? I thouught molecules were quantum objects as well... i.e.they don't have definite size.

 

[ZapperZ]

To me it is meaningful in a goal to model or simulate processes such as hydration and polymerization where you must track things over time. The model of electrons stuck inside a shell by an amount equal to their ionization energy, together with the normal coulomb force pushing protons apart, leads to the most common forms of hydrogen that are easy to draw and conceptualize (is there a spell checker in this application?).

Fine. Let's look at H2 molecule, shall we?

You missed one extremely important aspect of the H2 molecule - the existence of bonding and antibonding state. Look it up. It has quite a bit to do with the phase of the electronic wavefunction. This phase is completely missing in such classical picture of your model, and it means that you have no ability to make a meaningful model of it.

It also indicates that such attempts at producing such a simple picture is inadequate. The fact that we do have a good description of it without needing such simplistic (and incorrect) description is what is puzzling me as far as the need for such erroneous picture. I mean, it is not as if we are just now discovering H atom, and trying to make a model of it to describe it, as what occurred during the early history of quantum mechanics. We already know of a very good (and accurate) description of such systems. Why are we trying to take a large step backwards and produce such toy model when it isn't necessary?

This is very strange!

Zz.

 

[granpa]

hydrogen antibonding

looks very similar to how 'lone pairs' interact.(or are those 'nonbonding'?)

 

[Vanadium 50]

Also, the ortho- and para- states are related to the nuclear spins. Whatever it is you are trying to convey with your drawing, it involved the electron spins.

 

[edguy99]

Also, the ortho- and para- states are related to the nuclear spins. Whatever it is you are trying to convey with your drawing, it involved the electron spins.

Yes this is a very important element of the picture. Remember that the protons are almost 2000 times heavier then the electrons and are great big lugs at these timescales (attoseconds).

The electrons in para-hydrogen cannot rotate around each other as that would involve the rotation of the protons which would tear the molecule apart. In ortho-hydrogen, the electrons can rotate around a radius in the range of 70 pm (spin or form a torus in 3d towards the observer) while the protons just sit there. Hence the two types of hydrogen have different responses to magnets.

 

[Vanadium 50]

This sounds very speculative. Do you have any evidence for this picture of yours?

 

[edguy99]

You missed one extremely important aspect of the H2 molecule - the existence of bonding and antibonding state. Look it up. It has quite a bit to do with the phase of the electronic wavefunction. This phase is completely missing in such classical picture of your model, and it means that you have no ability to make a meaningful model of it.

...

Zz.

I'm sorry, but I am not sure the context of bonding or antibonding, say solid state or organic type chemistry? I was getting a lot of different things in my lookup.

 

[ZapperZ]

I'm sorry, but I am not sure the context of bonding or antibonding, say solid state or organic type chemistry? I was getting a lot of different things in my lookup.

Does it matter? Either scenario will indicate the inadequacy of your model.

The covalent bond that produces either the bonding or antibonding in Chemistry is one example. The bonding-antibonding BANDS in solid state physics would be another example. In both of these cases, the LACK of phase information in your naive model (or in any classical orbit model) will show a very glaring deficiency!

Zz.

 

[IPart]

I read the entire thread. Phew!

I have to say that I was struck by how tangential a lot of the discussion is. And if I may so, how pointless it is to let a discussion about QM degenerate into a discussion about posters' personal qualifications.

So here's my question to edguy99:
Can you summarize your question and specify articulately the physics framework you want to address the question in?

If I remember right, Feynman also said that a question well asked often answers itself.

 

[edguy99]

I read the entire thread. Phew!

I have to say that I was struck by how tangential a lot of the discussion is. And if I may so, how pointless it is to let a discussion about QM degenerate into a discussion about posters' personal qualifications.

So here's my question to edguy99:
Can you summarize your question and specify articulately the physics framework you want to address the question in?

If I remember right, Feynman also said that a question well asked often answers itself.

I certainly did not see anything in the thread of a personal nature and I am not sure what you mean.

If you want me to ask a question I guess it would be: Do you see anything in the pictures of hydrogen posted that you see as conflicting with real life measurements?

Zz posted a question on bonding that I had planned on respond to by expanding the discussion to carbon-carbon bonds where anti-bonding is often talked about. I am in the middle of doing animations with respect to making plastics out of ethylene so the discussion is both timely and relevant for me.

 

[ZapperZ]

I certainly did not see anything in the thread of a personal nature and I am not sure what you mean.

If you want me to ask a question I guess it would be: Do you see anything in the pictures of hydrogen posted that you see as conflicting with real life measurements?

Zz posted a question on bonding that I had planned on respond to by expanding the discussion to carbon-carbon bonds where anti-bonding is often talked about. I am in the middle of doing animations with respect to making plastics out of ethylene so the discussion is both timely and relevant for me.

Yet, you still have no even attempted to address what I wrote earlier about this whole thing:

The fact that we do have a good description of it without needing such simplistic (and incorrect) description is what is puzzling me as far as the need for such erroneous picture. I mean, it is not as if we are just now discovering H atom, and trying to make a model of it to describe it, as what occurred during the early history of quantum mechanics. We already know of a very good (and accurate) description of such systems. Why are we trying to take a large step backwards and produce such toy model when it isn't necessary?

Why are you doing this and why is it necessary, especially when it appears that all you're doing is a bunch of "patchwork" without any kind of First Principle foundation.

Zz.

 

[granpa]

are current theories sufficiently well developed that we could, if we had a computer big enough and powerful enough, simulate individual subatomic particles with sufficient accuracy that they would (in the simulation) form molecules and larger objects with all the properties that we see in the real world.

 

[nuby]

interesting question. I'd bet some super computers are working on something like that right now.

 

[ZapperZ]

are current theories sufficiently well developed that we could, if we had a computer big enough and powerful enough, simulate individual subatomic particles with sufficient accuracy that they would (in the simulation) form molecules and larger objects with all the properties that we see in the real world.

This is before I argue with you about "emergent phenomena" that I've talked about and the fallacy of trying to derive such phenomena by considering the interactions at the individual particle scale.

Zz.

 

[edguy99]

I got interested in a visual representation mostly from seeing real life pictures at the 1 angstrom level that appear to be showing some structure through IBM and other recent photos of Graphene.

 

[malawi_glenn]

I got interested in a visual representation mostly from seeing real life pictures at the 1 angstrom level that appear to be showing some structure through IBM and other recent photos of Graphene.

But do you understand the physics and technology that makes those pictures?

 

[ZapperZ]

I got interested in a visual representation mostly from seeing real life pictures at the 1 angstrom level that appear to be showing some structure through IBM and other recent photos of Graphene.

Then you should find an art forum, if that is all you care about.

The "visual representation" here has a lot of physics behind it that derived such visual representation. This isn't trivial and can't simply be dumbed down by your model.

Zz.

 

[granpa]

Why doesn’t the Electron crash into the proton??
We know in an H atom the e- is attracted to the + charge of the proton.
And it wants to get down to the "0 level" orbit.
But what makes that level zero – or why does e- stop going down?
Is there another force that counteracts the force of charge trying to pull them together?

Note: the intent of this thread is potential descriptions of why the electron does not crash into a proton. NOT how QM defines it or that QM can claim that no one can describe it. But how people do try to describe it. So explaining why an idea doesn't work should also be described in Non-QM terms. Everybody already knows that uncertainty and the math of QM does work, we do not need to be reminded.

I suppose you already know but just in case you dont:
the energy of the lowest level for any atom with 1 electron is proportional to RZ^2
where R is the Rydberg constant and Z is the charge of the nucleus.