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Postulate 2: When an electron revolves in any selected orbits, it neither emits nor absorbs energy . The energy of an electron in a particular orbit remains constant.

Thus, Bohr, by postulating this, removed the problems of Rutherford's atomic model as:

If the negatively charged electron revolves round the positive nucleus, it will continuously emit radiations. Thus, it will follow a spiral path and eventually will collapse. If it happens, the spectra of the atom should be continuous as it will radiate at all the frequences while collapsing. But, in practice, this doesn't happen and atom is stable.

  1. How?

  2. By postulating a statement, how could he solve the problem?

  3. What is the cause for his statement being correct?

  4. Why doesn't the electron lose or gain energy?

  5. Does electron follow his postulate?

  6. Or is there any physical intuition behind it?

Please help. (please give me a math-free explanation. I want the physical intuition.)

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2 Answers 2

Please read my answer here Collapse of the wave function and Heisenberg uncertainty where I address this part of the question.

1) there existed the spectra from hydrogen and other atoms that could be explained by quantized orbits

2) the hydrogen atom spectra were fitted with a series and the Bohr model explained the series

3) Postulates are as axioms for physics models, in addition for the axioms of the mathematical framework they are formulated in.

The Bohr model is an ad hoc model, describing the data but not really a theory since it could not be used except qualitatively for other atoms.

The model could accommodate the observations but physicists were not satisfied. Used to the elegance of mechanics and electrodynamics they were searching for differential equations that would give in their solution the same results as the Bohr model but be more general to be built into a theory. Schrodinger succeeded.

From then on the theory of quantum mechanics with its own postulates was developed, where the electron around the proton in the hydrogen atom is not in an orbit , but in a stable orbital, a probability locus for finding it at (x,y,z,t). It is postulate 6 in the list that posits stable orbitals.

Up to now the theory of quantum mechanics has been very successful, the QM postulates are validated as good choices fitting the mathematical models to data and making innumerable new predictions. It has given us from transistors and phones to computers and lasers, as the result of having fitted successfully how the underlying framework of matter works.

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You cannot understand quantum mechanics by intuition. A simple ans i can give is that like $F = ma$ in classical mechanics, there is Schrodinger equation in quantum mechanics and like momentum and position in classical mechanics in quantum mechanics you need wave functions to describe systems.. If in the Schrodinger equation the potential function is a function of position $x$ alone or then you can solve the equation by seperation of variables method and you will get The solution(wave function) $$\Psi{ (x,t)} =K(x) e^[\dfrac{-iEt}{\bar{h}}]$$ And probability density (which is defined as the product of the wave function with its complex conjugate) become time independent. The samething happens in calculating the expectation value of any dynamical variable,every expectation value is constant with time..though cannot understand these if you dont know atleast basic quantum mechanics..

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