Question

Write the main points of bohrs atomic model . Write any two limitations .

Answer 1

The orbits of the hydrogen atom which an electron travels have a set size and energy level. Therefore, the orbits are said to be quantized.
The size of the orbit's radius is directly proportional to the orbit’s energy state.
When an electron is in orbit the energy of the entire atom is at a constant rate.
When the electron transfers from one orbit another, this is when the energy level changes. This process of the electron's movement from one orbit to another is called a 'jump'.
The jumps of an electron deal with the emission and absorption of photons. The ways these photons are given off and taken in by the hydrogen's electron account for specific spectral lines of the hydrogen spectrum which deals with the atomic spectra.
Limitations ;
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.
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.