# The Bohr Model

marlon said:
Well, yes, ofcourse , but you still don't get the point do you???

The strong decrease in potential energy means what do you think ??? There is no solution for r = 0 because it is not physical so not worthy of mentioning here...

What do mean by a "solution at r=0"? You have a Schrodinger equation, with a Coulomb potential. You solve it. You get a set of discrete eigenstates and eigenvalues, the lowest of which is the ground state, which is stable. Just in the same way as one would for a harmonic oscillator, or pretty much any other potential. What does the fact that there's a divergence at r=0 have to do with anything?

Moose352 said:
Actually, Bohr's model also assumes that the electron orbits the nucleus. However, Bohr theorized that at certain discrete levels, the electron would not radiate energy, and therefore would be stable.

Yeah thats how I understand the Bohr model too,

Bohr postulated that electrons in atoms can only move around a nucleus in certain circular orbits which are stable without radiating energy. Each orbit has a definite energy level associated with it, and hence energy is only radiated when there is a transistion from an excited state to the ground state.

David

Check Chapter 38 of University Physics by Young and Freedman

This thread is sure getting interesting....but I'm really confused now. Cause one of you says one thing, the other opposes it and says something else....

I understand what all of you are saying....honestly. Like, I might still be in High School, but I'm known (from my parents) that I always increase my knowledge a little bit more so that I can understand what you guys are saying.

Can anyone tell me any book titles I can check at my local library so that I can read some more about this topic? Thank you.

Check the reference I gave in the above post, it should clear things up for you. You dont need to look at the Schrodinger equation to consider the Bohr model. Specifically look at page 1462 in the 11th edition. If your at high school you dont really need to be looking at the Schrodinger equation at all...... (well you dont in the UK anyway!).

See according to classical electromagnetic theory your quite right, the electrons (if you consider them in particle form) would emit EMR as they cirlced the nucleous, but Bohr postulated that they could in fact not do so if they where in stable circle orbits.... if you read the reference above you will see where some of the comments above are coming from .... quantum mechanics looks at electrons as waves rather than particles due to De Brogiles theory and later proof via electron diffraction.

davidmerritt said:
Check the reference I gave in the above post, it should clear things up for you. You dont need to look at the Schrodinger equation to consider the Bohr model. Specifically look at page 1462 in the 11th edition. If your at high school you dont really need to be looking at the Schrodinger equation at all...... (well you dont in the UK anyway!).

See according to classical electromagnetic theory your quite right, the electrons (if you consider them in particle form) would emit EMR as they cirlced the nucleous, but Bohr postulated that they could in fact not do so if they where in stable circle orbits.... if you read the reference above you will see where some of the comments above are coming from .... quantum mechanics looks at electrons as waves rather than particles due to De Brogiles theory and later proof via electron diffraction.

Okay, thanks! Oh, I get what you're saying about the electrons now.

P.S. I don't even know how I came up with the idea of electrons crashing into the nucleus when they emit EMR. It just sort of came to mind one day as I was thinking about it becaue of the great amount of energy electrons give off as they emit EMR. I'm going to see if I can get that book you're talking about at my local library or something.

dextercioby
Homework Helper
GodsChild086 said:
Okay, thanks! Oh, I get what you're saying about the electrons now.

P.S. I don't even know how I came up with the idea of electrons crashing into the nucleus when they emit EMR. It just sort of came to mind one day as I was thinking about it becaue of the great amount of energy electrons give off as they emit EMR. I'm going to see if I can get that book you're talking about at my local library or something.

The idea was viable and correct;happily we found that laws of classical electrodynamics do not apply at quantum/microscopical level,that's all.Those electrons don't emit radiation when the atom is stable and isolated from external interractions,as they should according to classical emectrodynamics.
Even these days people wonder how could the brilliant mind of Sir Ernest Rutherford came up with such a dumb idea...

So let me get this straight....the reason why the electrons (well atoms) would NOT crash into the nucleus when they emit EMR is because most atoms are very stable. (Just remembering something about atoms from Chemistry.)

dextercioby I wouldn't say it was a massive step from his particle scattering experiments, though it would have been interesting to work in Rutherfords lab during his time(P.s. I did my degree at the University of Manchester i.e. where rutherford did his work, lol they have a lecture theatre named after him nowadays)

He must of thought (along with Bohr) that is the mass is centered (i.e. in the nucleus) then the only sensible way of thinking about the movement of electrons is in fixed circular orbits. The big step for Bohr was to suggest that they wont radiate energy as they circle the nucleus, this is a big departure from classical electromagnetic theory (as said).

loandbehold said:
Not really. Surely if l=0 then you just have the -1/r term, which diverges to minus infinity at r=0, not at r=1.

Well keep in mind that we are discussing electrons that ORBIT around a nucleus...The Bohr model clearly states that $$L = n \hbar$$ for n = 1,2,3... So the value l = 0 (L =0 ) describes the attraction between two non-orbiting particles...

Also keep in mind that the Bohr-radius is calculated as that radius at which the probability of findinf the electron in its ground state is maximal...

regards
marlon

So let me get something else straight....

I forgot that in Physics 20 I learned something about strong and weak nuclear forces. So is it the strong nuclear force that holds those electrons in orbit so that they don't go crashing into the nucleus?

dextercioby
Homework Helper
GodsChild086 said:
So let me get something else straight....

I forgot that in Physics 20 I learned something about strong and weak nuclear forces. So is it the strong nuclear force that holds those electrons in orbit so that they don't go crashing into the nucleus?

No,the strong interraction only occurs at distances of about 10^-15 m (one fermi),while the electromagnetic interaction is responsable for the atom stability and it is universal,that means it occurs at any distance;the key is that electrons in atoms have close to zero probability of coming to within one fermi of the nucleus.They're most probably found at distances of Angstrom order (10^-10 m) which is 100000 times larger than the typical nuclear distance.
Going deeper into QFT,we say that electrons are leptons that do not "feel" the strong interraction.

Daniel.

The strong force holds baryons and mesons together, while the residual strong force will hold atomic nuclei together... Atoms are held together by electromagnetic interactions between the nucleus and the surrounding electrons. Also the angular momentum of the electrons contributes to this interaction...

regards
marlon