azimuthal quantum number

The azimuthal quantum number determines shape of orbitals and can uniquely identify a subshell if given with a principal quantum number.

$l$	subshell shape
0	s
1	p
2	d
3	f

Let $n$ be the energy level of the valence shell electron. For any electron in this atom, $0\le l\le n-1$.

The number of orbitals in a certain subshell (a certain $l$) can be obtained from $l^2+1$.