# Atomic spectra and atomic structure by Gerhard Herzberg

1. Oct 24, 2005

### Galaxy33

Hi! to everyone on the forum. I am new and did not really know where i should of posted this thread its not homework its just a question i have.

A friend of mine asked me a question about a book he read about (atomic spectra and atomic structure by Gerhard Herzberg). Gerhard Herzberg said that, in reality the electron revolves, not about the nucleus itself, but about a commen center of gravity; also the nucleus revolves about that center.

The question is, in 2005 is this view by Gerhard Herzberg still true? I did not know the answer so i posted it here.....

Galaxy......

2. Oct 24, 2005

### Conehead

Great question. Some physicists, during the advent of quantum mechanics, spent some time double checking but Herzberg is still correct.

Though the atomic nucleus greatly outweighs the electrons, the electrons still do some pulling--enough anyway to yank the whole atom (electrons and all) out of whack, even if just the smallest bit.

3. Oct 24, 2005

### nbo10

If you view the system classically, then yes the electron does revolve around the CM.

If you take the Qunatum view, the correct representation, then the question is ill-formed and can not be answered.

4. Oct 24, 2005

### ZapperZ

Staff Emeritus
And in what kind of observation/experiment/phenomenon does this "smallest bit" effect manifests itself?

Zz.

5. Oct 24, 2005

### Conehead

I'm assuming you're talking about HUP. Fine, this is a theoretical question and I'm going to keep assuming (unless asked otherwise) that Galaxy doesn't require proof of speed and position of the particle at the same time.

And, I might add, just because we can't nail down a mathematical snapshot of said particle doesn't mean that we don't know what it's doing. Feynman spends some time on this topic.

6. Oct 24, 2005

### nbo10

It has nothing to do with the Uncertainty principle. The electron, described by it's wavefunction, has a probability distribution that doesn't "revolve" around anything.

7. Oct 24, 2005

### ZapperZ

Staff Emeritus
What "mathematical snapshot" did you have in mind? The mathematical description of an atom has no such trajectory. One only needs to look at the solution fo the hydrogen atom to know this. And these were not derived out of the HUP either.

Zz.

8. Oct 24, 2005

### Conehead

Where is the electron distributed? Does it not have a position?

Based on the responses I'm way off on this, somehow. If that's the case give the proper answer. I'd hate argue bad info any longer than I have to.

Last edited: Oct 24, 2005
9. Oct 24, 2005

### ZapperZ

Staff Emeritus
This goes to the foundation of QM and why the Schrodinger Cat thought experiment came into being!

It does NOT have a definite position till it is measured. The s-orbital is a spherical distribution of ONE electron. You get this by solving the orbital part of the Schrodinger equation. The electron IS distributed all over the place simultaneously. This is what makes QM highly non-intuitive for anyone who skip the mathematical formalism.

How do you know such a description is valid? Besides the fact that QM gave unbelievably accurate energy spectrum of many atoms and molecules (something classical mechanics could not), we also have evidence from how bonding forms, especially in the formation of bonding and antibonding states. Such phenomenon has no intuitive counterpart in classical mechanics.

Zz.

10. Oct 24, 2005

### Conehead

So, I'm assuming that a thrown photon's trajectory is also a matter of probability?

11. Oct 24, 2005

### Gokul43201

Staff Emeritus
To say something about the OP's question : Yes, you can decompose the Schrodinger Equation for the H-atom into two parts - one dealing with the center of mass motion and the other dealing with the relative motion - using the standard change of variables :

$$\mu = \frac {m_1m_2} {m_1+m_2}~;~~M = m_1 + m_2~;~~r = |r_1 - r_2|~;~~R = \frac{m_1 r_1 + m_2 r_2}{m_1+m_2}$$

This makes - in the case of the H-atom - a very tiny change to the Hamiltonia.

Last edited: Oct 24, 2005
12. Oct 24, 2005

### ZapperZ

Staff Emeritus
I wouldn't know, since I have no idea what a "thrown photon" is.

Zz.

13. Oct 24, 2005

### Conehead

When an electron drops to a lower energy level it releases a photon

Did I do something to irritate you?

14. Oct 24, 2005

### ZapperZ

Staff Emeritus
No. I'm responding to what you have said. Is it wrong for me to get clarification of what you are saying or claiming? I have never seen the phrase "thrown photon" in all my years in this field. I have also haven't seen any experimental evidence to back your claim earlier of ".... electrons still do some pulling--enough anyway to yank the whole atom (electrons and all) out of whack, even if just the smallest bit.. "

So a photon emitted by an atomic transition is what you called "thrown photon"? I'm not sure why this would be relevant for this thread. Once photons are emitted one can very much invoke classical optics.

Zz.

15. Oct 24, 2005

### nbo10

Don't take thing's personally.

Life is in the details. When you ask a vague question you're going to get a vague answer. When you ask a general, non-specific, or ill-worded question, you'll find the answer you get isn't going to be helpful.

Photons are very different from electrons.

16. Oct 24, 2005

### Conehead

Oh, I wasn't taking anything personally. Just making sure someone else wasn't. I have very colloquial conversations with working physicists everyday with far better results than just now. But I have a way of not making sense sometimes.

Thanks for the information. Ciao.

17. Oct 24, 2005

### Galaxy33

Thanks to everyone who answered my question, but can i assume that the answer was yes, as Conehead stated (some physicists during the advent of quantum mecanics, spent some time double checking but Herzberg is still correct) ?

Titana.............

Last edited: Oct 25, 2005
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