These guys, you should definitely know. Now, for example, s corresponds to l equals zero. When our quantum number is N equals one, we get one minus 10. So if our electron is found with a principal quantum number of one, that means it must be in subsshell l equals zero, because l equals one minus one gives you zero. Likewise, p represents a subshell of l equals 1d represents a subsshell of l equals two, f represents a subshell of l equals three, and so on. Now, every subshell has a certain shape.