Problem: If an atom has an electron in the n = 4 state with ml = 2, what are the possible values of l?

• Principal Quantum Number (n): deals with the size and energy of the atomic orbital. 

The possible values for n are 1 to ∞.

• Angular Momentum Quantum Number (l): deals with the shape of the atomic orbital. 

The possible values for l are 0 to (n – 1).

• Magnetic Quantum Number (m_l): deals with the orientation of the atomic orbital in 3D space. 

The possible values for m_l is the range of l: –l to +l.