For the principal quantum number, n, its corresponding sets of magnetic quantum, m, values depend on the angular quantum values, l. For n=2, the values of l are from 0 to (n-1), which are 0 and 1. For each value of l, the m value that corresponds to it is given by m = -l, ..., 0, ..., +l. This gives a set of m values equial to m = -1, 0, 1.
