In Bohr-Sommerfeld atomic model, the space around nucleus is quantised, i.e. the distribution
of electrons in these orbits is in accordance with quantum number.
|Fig 1. Vector L traces a cone
around vector B.
The electron orbital angular momentum vector L traces a cone around B such that angle ϴ between L and B remains constant as shown in figure.
According to the quantisation principle :
This angle ϴ between L and the z-axes is determined by the quantum number ‘l’ & ‘ml’.
In other words, the angular momentum vector L can have (2n+1) discrete orientations, with respect to the magnetic field.
The quantisation of the orientation of atom in space is known as space quantisation.
|Fig 2.Space quantisation of
vector L corresponding to L=2.
For l=2 we have,
Note:- L can never be aligned exactly parallel or antiparallel to B, since |ml| is always smaller than √l(l+1).
This is Space Quantisation. You can ask any question related to this post in comment section.