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A drawback (and a major one) of Rutherford's model was that the electrons, being accelerated charged particles, would gradually spiral into the nucleus and collapse into it. My question is how did Bohr rectify this drawback in his own model.

In Bohr's model too, electrons move in a circular path, which means they are accelerated. Thus, going by Electromagnetic theory of Maxwell, those accelerated electrons should radiate out their energy, and collapse into the nucleus, just like they did in Rutherford's model. However every book mentions that this does not happen in Bohr's model. Why not?

Please tell me where I am wrong, because this problem has been disturbing me for quite long now.

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    $\begingroup$ What books are you reading? en.wikipedia.org/wiki/Bohr_model#Shortcomings last bullet point $\endgroup$ – orthocresol♦ Jun 3 '17 at 20:05
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    $\begingroup$ Nobody says the Bohr model is right. At the time it was a step, but with issues needing quantum mechanics to solve... $\endgroup$ – Jon Custer Jun 3 '17 at 23:32
  • $\begingroup$ Really a question for Physics SE and answered there already I think here and here $\endgroup$ – StephenG Jun 4 '17 at 3:00
  • $\begingroup$ Thank everyone for their respective inputs. I am new to stack exchange, and searching for a particular question does not seem to be easy here. $\endgroup$ – Aumkaar Pranav Jun 7 '17 at 13:36
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As a matter of fact, Bohr literally went past around this issue. In 1913, he proposed his model postulating electrons could only have certain classical motions:

  1. Electrons in atoms orbit the nucleus.

  2. The electrons can only orbit stably, without radiating, in certain orbits (called by Bohr the "stationary orbits") at a certain discrete set of distances from the nucleus. These orbits are associated with definite energies and are also called energy shells or energy levels. In these orbits, the electron's acceleration does not result in radiation and energy loss as required by classical electromagnetic theory (This was based upon Planck's quantum theory of radiation).

  3. Electrons can only gain and lose energy by jumping from one allowed orbit to another, absorbing or emitting electromagnetic radiation with a frequency ν determined by the energy difference of the levels according to the Planck relation: $$ \Delta {E}=E_{2}-E_{1}=h\nu \ $$

where h is Planck's constant.

As remarked above, these are postulates (statements assumed to be true from which further reasoning follows), and (even though that part was left unexplained), it's acceptance was due to the fact it explained correctly many experimental results. It was further displaced by the modern quantum theory.

Hope it helps, it also puzzled me a few years ago! :P

Reference: https://en.wikipedia.org/wiki/Bohr_model

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  • $\begingroup$ So, exactly what Bohr did is that he assumed that the drawback didn't exist? $\endgroup$ – Aumkaar Pranav Jun 7 '17 at 13:34
  • $\begingroup$ @AumkaarPranavShukla I'd rather say he knew it was incomplete but felt the explanation for it could be found later by another person $\endgroup$ – Ad115 Jun 28 '17 at 5:16

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