Electron energy: forever?

[Mellinia]

If electrons exist as standing waves in an atom, how:

1)is the region of probability denity stay fixed?

2)does the electron not crash into the nucleus?

3)does the overall energy of the atom stay fixed?

4)Newtonian physics fail in explaining atomic mechanics?

[steevey]

If electrons exist as standing waves in an atom, how:

1)is the region of probability denity stay fixed?

2)does the electron not crash into the nucleus?

3)does the overall energy of the atom stay fixed?

4)Newtonian physics fail in explaining atomic mechanics?

 

None of these are permanent, not even some things in 4. At any moment, an electron could gain energy from a photon and jump the a higher energy level changing where it's probability to be found is. And, because an electron is a standing wave of existence and not a particle, it appears at its most probable locations and usually not in the nucleus. If an electron were actually just a particle, THEN it would fall into the nucleus. Sometimes an electron can be in the nucleus, but its very unlikely in an atom.

 

Newtonian physics still applies in some ways for 1, whenever an electron exerts an electro-magnetic force an another particle such as a proton, the proton still exerts the same amount of electo-magnetic force back on the electron.

 

The only reason the quantum world appears to be separated from the classical world is because on the very large scale, its nearly impossible for a particle such as a bound electron to jump any sort of noticeable distance away from its most probable location to appear. And its much less probable than enough noticeable matter of an object would do it simultaneously as to cause the object to appear to be teleporting.

 

And, unless an electron gets converted into pure energy or a number of other particles, it will always be its own wave and continue to pop in and out.

 

Honestly, the point of the electron cloud model is that an electron itself isn't actually moving like a planet around a star at all.

Edited January 23, 2011 by steevey

[lemur]

Honestly, the point of the electron cloud model is that an electron itself isn't actually moving like a planet around a star at all.

I have to start by once again saying that I think your summations of QM aspects are extremely clear and concise from the limited perspective I have from what I've read.

 

I am post, however, to say that at least for me, the tension with QM and Newtonian mechanics is not whether electron clouds resemble satellite motion within a gravity field. The issue is that SOME logical patterns of motion should explain how the electron "teleports" and why. If it behaves as wave-energy instead of a moving point, that is comprehensible. But if people settle on a model of the wave's motion that teleportation/tunneling is a mode by which it transports itself, then there should be some mechanical model to explain how/why it would do this and what would explain why the probability of it popping-up within a certain area is more likely, imo.

 

 

[swansont]

If electrons exist as standing waves in an atom, how:

1)is the region of probability denity stay fixed?

2)does the electron not crash into the nucleus?

3)does the overall energy of the atom stay fixed?

4)Newtonian physics fail in explaining atomic mechanics?

 

The electron as a standing wave was part of the Bohr model, which was discarded because it was wrong. The probability density is fixed for a given state, the electron has some probability of being found in the nucleus, the energy is fixed and Newtonian physics indeed fails; there is no well-defined trajectory of the electron.

[lemur]

Newtonian physics indeed fails; there is no well-defined trajectory of the electron.

Ok, but why aren't there any proposed models for how the electron's trajectory is as it is?

[swansont]

Ok, but why aren't there any proposed models for how the electron's trajectory is as it is?

 

There were, but they don't work. Quantum theory does a much better job.

[lemur]

There were, but they don't work. Quantum theory does a much better job.

How does quantum theory explain electron trajectory between "sightings" then? My impression was that it could only predict its appearance in terms of probability but that no explanatory model was offered as to how it gets between observed positions.

 

 

 

[steevey]

Newtonian physics indeed fails

 

Most of it does, but what about the still prevalent property of newton's third law of motion? An electron exerting an electro-magnetic force on a proton will receive the same amount of electro-magnetic force from that proton whether they are waves or particles.

 

The electron as a standing wave was part of the Bohr model, which was discarded because it was wrong.

 

I thought the Bohr model was that solar system-like model which just shows how energy and movement is quantized at the atomic level.

 

Electrons are still described as waves surrounding the nucleus aren't they? They are more like clouds which represent the electrons as waves and the highest areas of probability for appearing as particles. I think its called the wave mechanics model

Edited January 23, 2011 by steevey

[Mellinia]

If I heat an atom, would the entire atom self-vibrate or only the electron cloud would vibrate on it's own, indirectly causing the nucleus to move in accordance of the third law of motion??

[swansont]

How does quantum theory explain electron trajectory between "sightings" then? My impression was that it could only predict its appearance in terms of probability but that no explanatory model was offered as to how it gets between observed positions.

 

The wave function evolves in time.

 

I thought the Bohr model was that solar system-like model which just shows how energy and movement is quantized at the atomic level.

 

Electrons are still described as waves surrounding the nucleus aren't they? They are more like clouds which represent the electrons as waves and the highest areas of probability for appearing as particles. I think its called the wave mechanics model

 

They are modeled as standing waves in the Bohr model, but not in QM.

 

If I heat an atom, would the entire atom self-vibrate or only the electron cloud would vibrate on it's own, indirectly causing the nucleus to move in accordance of the third law of motion??

 

"Heating an atom" is as awkward phrase; what you describe is raising the temperature, which is the property of a collection of atoms. For an individual atom, the whole thing will move.

[steevey]

They are modeled as standing waves in the Bohr model, but not in QM.

 

Aren't electrons also waves in the new model? They are described more like clouds with specific shapes for given properties, but they have those shapes because of the wave nature of elementary particles don't they? Otherwise, how could a single particle electron be an entire cloud of superpositions?

Edited January 23, 2011 by steevey

[swansont]

Yes. It's true in all of quantum mechanics, not just in the atomic model.

[steevey]

Yes. It's true in all of quantum mechanics, not just in the atomic model.

 

I don't get what was wrong with Bohr's model then. Was it that the only shapes were spheres instead of things like dumbbells and toruses and double dumbbells?

[mississippichem]

I don't get what was wrong with Bohr's model then. Was it that the only shapes were spheres instead of things like dumbbells and toruses and double dumbbells?

 

The predicted angular momentum of the electron was wrong for one thing.

[swansont]

There are also missing states and no way to account for the transition probabilities.

[lemur]

The wave function evolves in time.

How does that explain how the electron tunnels between sightings within the wave function? Isn't the wave function just a probability-area for sightings of the electron as a point-particle, or have I understood it wrong?

 

They are modeled as standing waves in the Bohr model, but not in QM.

So if it's not a point-particle or a standing wave, what does QM say it is? Or does QM only deal with concepts at an instrumental level and refused to model electrons in a qualitative way whatsoever? If so, is there some other approach that can move forward with qualitative modeling in some way (please)?

 

"Heating an atom" is as awkward phrase; what you describe is raising the temperature, which is the property of a collection of atoms. For an individual atom, the whole thing will move.

I thought the pertinent question was about what the relationship of the electrons are to the nucleus in absorbing energy as heat (vibration). It seems logical that energy would have to affect the electrons and the electrons would transfer the energy to the nucleus, but maybe energy can penetrate the electrons and directly animate the nucleus. Are photons an exclusive mechanism for energy transfer among atoms or can they still collide with each other despite theoretical advances?

 

 

[swansont]

How does that explain how the electron tunnels between sightings within the wave function? Isn't the wave function just a probability-area for sightings of the electron as a point-particle, or have I understood it wrong?

"Sightings within the wave function?"

 

Yes, the wave function tells you probability. It's not a physical thing.

 

 

So if it's not a point-particle or a standing wave, what does QM say it is? Or does QM only deal with concepts at an instrumental level and refused to model electrons in a qualitative way whatsoever? If so, is there some other approach that can move forward with qualitative modeling in some way (please)?

 

A wave.

 

I thought the pertinent question was about what the relationship of the electrons are to the nucleus in absorbing energy as heat (vibration). It seems logical that energy would have to affect the electrons and the electrons would transfer the energy to the nucleus, but maybe energy can penetrate the electrons and directly animate the nucleus. Are photons an exclusive mechanism for energy transfer among atoms or can they still collide with each other despite theoretical advances?

 

Atoms can collide with each other. It's an electromagnetic interaction. I don't know what "energy can penetrate the electrons and directly animate the nucleus" means.

[steevey]

Atoms can collide with each other. It's an electromagnetic interaction. I don't know what "energy can penetrate the electrons and directly animate the nucleus" means.

 

I think he's pointing out that because an electron as a wave can surround the nucleus, doesn't a photon have to pass right through the electron to come into contact with the nucleus?

 

But I think what would happen is that the electron would hit the photon and get re-emitted in a random direction which usually doesn't hit the nucleus, and if it did the photon would get re-emitted anyway.

Edited January 24, 2011 by steevey

[swansont]

I think he's pointing out that because an electron as a wave can surround the nucleus, doesn't a photon have to pass right through the electron to come into contact with the nucleus?

 

But I think what would happen is that the electron would hit the photon and get re-emitted in a random direction which usually doesn't hit the nucleus, and if it did the photon would get re-emitted anyway.

 

Since the topic was vibration and scattering, I didn't think it was. lemur is free to clarify if that was indeed the case.

[lemur]

Since the topic was vibration and scattering, I didn't think it was. lemur is free to clarify if that was indeed the case.

That's what I meant; i.e. whether photons are capable of passing through the electrons and directly reaching the nucleus or whether all photons have to first be absorbed by the electrons before that energy can get translated into motion/vibration of the nucleus, presumably by means of the electrostatic tethering of the electrons to the nucleus.

 

Thanks for your other post, btw. So, by "a wave," you meant that the electrons are not static but orbit, though they do so as waves that are never out of phase (hence the discreteness of levels, correct?). I've read this before but I sometimes get confused which theory claims what and why. When people start saying the QM basically disproves everything without stating the alternative model it proposes, I start glazing over with the claims of pure-math modeling that, to me, are not sufficient to describe what (could) be actually going on to cause the numbers.

 

It's also my impression that QM restricts itself to talking in terms of probabilities of location of "electron sightings" to avoid even getting into the question of how electrons might get from one sighting to the next. The problem is that I don't see how anything can get from one point to another without some kind of line between the two points. If teleporting is real, it would be nice to have some kind of explanation of how the electrons do it, perhaps by being something akin to shimmering reflections on the surface of a wave?

[swansont]

That's what I meant; i.e. whether photons are capable of passing through the electrons and directly reaching the nucleus or whether all photons have to first be absorbed by the electrons before that energy can get translated into motion/vibration of the nucleus, presumably by means of the electrostatic tethering of the electrons to the nucleus.

 

The electrons and nucleus interact via the electromagnetic force, and high-energy photons can be absorbed by the nucleus.

 

 

Thanks for your other post, btw. So, by "a wave," you meant that the electrons are not static but orbit, though they do so as waves that are never out of phase (hence the discreteness of levels, correct?). I've read this before but I sometimes get confused which theory claims what and why. When people start saying the QM basically disproves everything without stating the alternative model it proposes, I start glazing over with the claims of pure-math modeling that, to me, are not sufficient to describe what (could) be actually going on to cause the numbers.

 

Discussing orbits is dangerous since it tends to conjure up images of a planetary system. The unfortunate problem is that one tends to try and construct a mental model based on knowledge of classical physics, and those will always fail at some point.

[steevey]

The electrons and nucleus interact via the electromagnetic force, and high-energy photons can be absorbed by the nucleus.

 

 

So what color do you get from a photon that has hit the nucleus?

 

And wait, "high energy"? So the only way an electron could even get to the nucleus past an electron is if it had high energy? Why does that matter?

Edited January 25, 2011 by steevey

[mississippichem]

So what color do you get from a photon that has hit the nucleus?

 

Well, the observed color of the emission that follows the nucleus becoming excited would probably be "gamma-colored" i.e. a much higher frequency of light than humans [or any other creatures for that matter I safely assume] can see. Nuclear transitions are really high energy when compared the electron transitions which corresponds to much higher frequencies.

[lemur]

Well, the observed color of the emission that follows the nucleus becoming excited would probably be "gamma-colored" i.e. a much higher frequency of light than humans [or any other creatures for that matter I safely assume] can see. Nuclear transitions are really high energy when compared the electron transitions which corresponds to much higher frequencies.

So electrons don't really exist for gamma rays? And all other photon frequencies interact with the electrons, which in turn interact with the nucleus? What would the filtering-factor be that allows some photons through and others to get absorbed by the electrons?

 

Swanson, "orbits" may "conjure up" the planetary model but what better word is there to describe a wave going around a nucleus?

 

 

 

[swansont]

So electrons don't really exist for gamma rays? And all other photon frequencies interact with the electrons, which in turn interact with the nucleus? What would the filtering-factor be that allows some photons through and others to get absorbed by the electrons?

 

A high-energy photon will result in ionization if the interaction includes the electron.

 

Swanson, "orbits" may "conjure up" the planetary model but what better word is there to describe a wave going around a nucleus?

 

"Going around" is also gives a false impression. In an S orbital (that's the term for them), there is zero angular momentum. There's no analogy to a classical "going around" at all.