In reply to Xavier Luminous's message of Fri, 30 Mar 2012 11:32:30 +0200: Hi, [snip] >> The reason this doesn't happen is not because the Bohr model is impossible. >> The >> reason is that a smaller orbit than the "ground state" would require a >> change in >> angular momentum of the electron that is less than the angular momentum of a >> photon, hence a photon can't be formed to carry away the difference in >> angular >> momentum that shrinkage below the ground state would require. Which in turn >> neatly explains why photon emission stops upon achieving the ground state. > >The picture that electrons orbit an atom makes no sense whatsoever.
Not what I said. I said "can" not "always do". >Your description works for simple atoms, but fails to account for may >effects. Here's a good list from Wikipedia of things the Bohr model >has problems with: Not relevant. [snip] >- The model also violates the uncertainty principle in that it >considers electrons to have known orbits and definite radius, two >things which can not be directly known at once. See section at the bottom of http://rvanspaa.freehostia.com/theory-paper.html > >- Doublets and Triplets: Appear in the spectra of some atoms: Very >close pairs of lines. Bohrs model cannot say why some energy levels >should be very close together. Once again, *can* not *always do*. > >- Multi-electron Atoms: dont have energy levels predicted by the >model. It doesnt work for (neutral) helium. > >(Off the top of my head this doesn't explain the exclusion principle either.) Does QM provide a *physical* explanation for the Pauli exclusion principle or just accept and use it? > >In short, quantum mechanics makes up for all the shortcomings of this >description and we should really abandon thinking of atoms as >electrons orbiting a nucleus. > >> In short this argument doesn't constitute the requested proof. In short the arguments presented still doesn't constitute the *requested* proof. In fact you are studiously ignoring the request altogether. > >Hopefully the above list is sufficient. Unfortunately not, as you are answering the question you *expect* to be asked, rather than the question that was *actually* asked. (you would make a good politician ;) [snip] >> Note that I didn't say that the Bohr model was "the" solution. I only >> requested >> that you show that it couldn't be a *particular* solution. IOW I'm asking >> that >> you show that it can *never* happen. > >You're correct that the Bohr model can be a particular solution to >explain some atomic features. Once again you appear to miss the point. The point is that it's not an either/or situation. Sometimes an electron can take up a Bohr orbit fleetingly, IOW it's not forbidden by the Schrödinger equation. The question is, can you prove this statement wrong? It's a matter of mathematics, either the function describing a Bohr orbit satisfies the Schrödinger equation or it doesn't. IOW is it a particular (though not general) solution? > My problem with it is that it makes you >think of electrons as classical particles instead of quantum >mechanical objects. This thinking, IMHO, should be eliminated. You may be correct that electrons are not particles, however I didn't say that they were. (Then again, what's the definition of a particle, and what is it exactly that hits the screen and excites the phosphors in old style TV sets? ;) > >> BTW exactly how is electron cloud density measured? (IOW how do you know >> that QM >> predictions thereof are correct?) > >You take pictures! Here are two, hopefully they're not paywalled. > >http://www.chymist.com/Imaging%20atomic%20orbitals.pdf >http://arxiv.org/pdf/cond-mat/0107195 > >A little bird told me while writing this that you can look at the >diffraction of ultrashort pulses and reconstruct other orbitals, but I >didn't look for a paper. > >>>Again, electrons don't orbit an atom. >> (Usually) > >EVER! :) Rydberg atoms? Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/project.html
