Limitations of Bohr's model of the atom
- Bohr's biggest contribution in his model was to introduce quantum principles to classical physics, but his model had a few limitations:
- Spectra of Large atoms:
- The Bohr model could only successfully explain the hydrogen spectrum.
- It could NOT accurately calculate the spectral lines of larger atoms.
- The model only worked for hydrogen-like atoms
- That is, if the atom had only one electron.
- Relative Spectra Intensity
- Bohr's model could not explain why the intensity of the spectra lines were NOT all equal.
- This suggests that some transitions are favoured more than others.
- Bohr's model could not explain why the intensity of the spectra lines were NOT all equal.
- Hyperfine spectral lines
- With better equipment and careful observation, it was found that there were previously undiscovered spectral lines
- These were named Hyperfine lines and they accompanied the other more visible lines.
- Bohr's model could not explain why this was the case due to the lack of equipment and development in quantum physics.
- The reason for these lines is actually because of a hyperfine structure of atoms.
- Solved through developments into Matrix Mechanics
- The Zeeman effect
- It was found that, when hydrogen gas was excited in a magnetic field, the produced emission spectrum was split.
- Bohr's model could not account for this
- Solved by accounting for the existence of a tiny magnetic moment of each electron.
- Stationary states
- Although Bohr stated that electrons were in stationary states, he could not explain why.
- The reason is covered later
- Although Bohr stated that electrons were in stationary states, he could not explain why.
- Mixture of Sciences
- The Bohr model was a mixture of quantum and classical physics
- This is an issue because it was thought that quantum physics was completely irrelevant and different to classical physics.
HINT: A useful mnemonic for remembering these is: Some Retards Have Zebra Stripes.
page revision: 3, last edited: 29 Oct 2011 12:31