There are four quantum numbers (n, l, ml, ms).
No two electrons in the same atom can have the same four quantum
numbers. Each quantum number describes a different aspect of the electron and its orbital. These numbers are obtained from the solution of the Schrödinger Equation for atoms in spherical coordinates.
n, the principle quantum number
n tells
you about the size of the orbital. It is related to how far the
electron is from the atom. It is also related to the energy of the
electron. ncan be any positive integer number. An orbital has n−1radial nodes as well, which describe a radius at which the probability of finding the electron is 0.
l, azimuthal quantum number
lt tells you about the angular momentum
of the electron in the orbital. It defines the shape of the orbital.
lt can be any integer between (and including) 0 and (n−1). Each orbital has lplanar nodes.
Some examples of orbitals with different l:
l=0is an s orbital, with no planar nodes.
l=1gives a p orbital, which has one planar node.
ml, magnetic quantum number
ml
tells you about the angular momentum projected on to the z axis. It
tells you of the orientation of the orbital. It can be any integer
between −l and l.
l=1 has 3 different (but degenerate) ml possible values:-1,0 or 1.
px
py
pz
ms spin projection quantum number
mstells you about the spin of the electron. An electron is a fermion, a type of quantum particle which is only allowed to have msequal to -1/2 or 1/2.
