# Is Heisenberg uncertainty principle really a demerit of Bohr model?

My teacher taught that Heisenberg's uncertainty principle is a demerit of Bohr atomic model.

But as the below paragraph from the article What Is Heisenbergâ€™s Uncertainty Principle? says and as per my thinking Heisenberg's uncertainty principle tells about the uncertainty, if we try to do some practical observation; while what Bohr told us by his formulas was almost fully theoretically derived. The paragraph basically tells that when photon strikes any subatomic particle then change in velocity occurs and uncertainty in position is incurred:

One way to think about the uncertainty principle is as an extension of how we see and measure things in the everyday world. You can read these words because particles of light, photons, have bounced off the screen or paper and reached your eyes. Each photon on that path carries with it some information about the surface it has bounced from, at the speed of light. Seeing a subatomic particle, such as an electron, is not so simple. You might similarly bounce a photon off it and then hope to detect that photon with an instrument. But chances are that the photon will impart some momentum to the electron as it hits it and change the path of the particle you are trying to measure. Or else, given that quantum particles often move so fast, the electron may no longer be in the place it was when the photon originally bounced off it. Either way, your observation of either position or momentum will be inaccurate and, more important, the act of observation affects the particle being observed.

Is Heisenberg's uncertainty principle really a demerit of Bohr model?

### Reference

• ...and it's still not rewritten... – Mithoron Sep 17 '17 at 18:08

Furthermore, Bohr's model is actually very empirical. In particular, one of its most important considerations is that the angular momentum of the electrons around an atom obey the formula $m_evr=n\hbar$, where $n$ is the positive integer responsible for introducing quantization to his model. However, this is just a postulated equation, with no rigorous derivation. It was chosen because it happened to describe the emission spectrum of hydrogen exceedingly well, so he knew it was right in at least some regime, but had no proof for it.