The first assumption of the Bohr atomic model states that 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. Electrons can only gain and lose energy by jumping from one allowed orbit to another. source

Someone pointed out a conceptual problem with this assumption: "If an electron is in a stationary state, it would not collapse." By calling it a "stationary orbit", does Bohr mean the electron orbital will never increase or decrease in energy or radius?

In other words, does the Bohr model say that the electrons will forever stay in the same stationary orbits? Is this the reason why the Bohr model was determined to be incorrect?

Or, does the Bohr model say that an electron can jump from one orbit to another, and thereby gain and lose energy? If so, under what conditions?

This question differs from this related question because it asks about the Bohr model, not about the planetary model.


closed as unclear what you're asking by Emilio Pisanty, user36790, heather, Gert, Jon Custer Sep 14 '16 at 12:39

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  • $\begingroup$ @JohnRennie Why is my question a duplicate of the one you pointed out?Mine is about the Bohr model, not the planetary model. Thank you! $\endgroup$ – Gloglo Sep 14 '16 at 8:07
  • $\begingroup$ @ Gloria your question isn't particularly clear, either. $\endgroup$ – Emilio Pisanty Sep 14 '16 at 8:17
  • $\begingroup$ @EmilioPisanty Thank you, I have tried to edit the question. $\endgroup$ – Gloglo Sep 14 '16 at 8:30
  • $\begingroup$ Sorry, I still have no idea what it is you're actually asking. What do you mean by "stationary state" and "collapse", why do you think "if an electron is in a stationary state, it would not tend to collapse", and why do you think that's a problem? $\endgroup$ – Emilio Pisanty Sep 14 '16 at 9:55
  • $\begingroup$ @EmilioPisanty By stationary state I mean orbit. I don't understand what makes an electron jump from one level of energy to a lower level of energy.I know that this must happen because we have a spectrum, so electromagnetic radiation. What are the causes of this change of energy's level? Thank you! $\endgroup$ – Gloglo Sep 14 '16 at 10:06

Bohr's atomic model is an approach to describe the hydrogen atom effectively. The model holds neither in classical nor in quantum physics completely. It is an effective model that describes the emission spectrum lines as transitions between the electron shells. It describes the electron shells of a hydrogen atom reasonably well, but fails completely when going to heavier (higher Z) atoms.

I found this formulation of the first two postulates of Bohr:

  1. Electrons in an atom exist in STATIONARY STATES.

    • Bohr stated that electrons orbit the nucleus WITHOUT emitting EM radiation.
    • Any permanent change in their motion must be accompanied by a complete transition from one stationary state to another.
    • Note that Bohr could NOT explain this.
  2. Transmission between stationary states produces/absorbs EM Radiation.

    • When an electron moves between stationary states, it is accompanied by the emission or absorption of a photon.
    • This photon's energy is given by ΔE=hf
    • Thus, EM radiation is produced by the movement of electrons between energy states which account for Planck's "atomic oscillators."

Source: http://nsb.wikidot.com/pl-9-8-1-3 -160814 12:04

The transition between orbits is an integral part of Bohr's model. But I would not try to explain the physics of the transition mechanism in this model. It is only an effective description of the hydrogen atom - not a physically correct one.


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