For p-subshell we have the value of angular quantum number as l = 1 & the degenerate orbitals are numbered from -l to +l.
Therefore here we have -1,0,+1 as the three degenerate orbitals of p subshell.
This is in accordance with the Schrodinger's model that allows the electron to occupy a three dimensional space. It therefore requires three quantum numbers, to describe the orbitals in which electrons can be found. The three coordinates that come from Schrodinger's wave equations are the principal (n), angular (l), and magnetic (m) quantum numbers.
These quantum numbers decide the shape, size and orientation in space of the orbitals on an atom.
