Give the set of four quantum numbers that represent the last electron added (using the aufbau principle to the cl atom.

An element has four quantum numbers associated with it. We have

1. principal quantum number ()
2. azimuthal quantum number ()
3. magnetic quantum number ()
4. spin quantum number ()

To look for each quantum  number of Chlorine (Cl), we mus first recall its electronic configuration: .

1. For , we need to look for its highest energy level or by simply checking the period that the element belongs to. So for this case, it's .

2. For , we need to look for the sublevel where the last electron was assigned. The sublevels, p, d, f are assigned to a value of 0, 1, 2, and 3, respectively. Since the last electron was assigned in p, then .

3. And for , the number of orbitals present in Cl is . The possible magnetic quantum numbers for are -1, 0, +1. Since there 5 electrons we count starting at -1. So, we have , we need to determine the spin. Since we have 5 electrons, all the arrows upward are filled in. That means the fifth electron has a spin of +1/2. 

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