The orbit shapes and various angles to the magnetic field could only have certain shapes, similar to an electron being in a certain orbit. As an example, the fourth orbit in a hydrogen atom can have only three possible shapes and seven possible traits. These added states allowed more possibilities for different spectral lines to appear. This brought the model of the atom into closer agreement with experimental data.
The conditions of the state of the orbit are described by quantum numbers. The three states discussed so far are: orbit number (n), orbit shape (l) and orbit tilt (m).
In 1924 an Austrian physicist, Wolfgang Pauli predicted that an electron should spin (kind of like a top) while it is orbiting around the nucleus. The electron can spin in either of two direction. This spin was assigned a fourth quantum number: electron spin (s).