What is the third quantum number of a 3s 2 electron in phosphorus?

In phosphorus, which has the electron configuration of 1s² 2s² 2p⁶ 3s² 3p³, the third quantum number refers to the magnetic quantum number (mₗ) associated with the s orbital. For an s orbital, the magnetic quantum number can only be 0, indicating that the orbital is spherical and has no angular momentum. Therefore, the third quantum number (mₗ) for a 3s² electron in phosphorus is 0.