Cu: [Ar]3d10 4 s1
2) Focus on valence electrons: those are outermost electrons and, therefor, the first to lose an atom to form an ion.
In this case the only valence electron is 4s1.
The feasible quantun numbers for that electron are.
n (principal quantum number or energy level) = 4
l (Azimuthal quantum number)= 0 (this is because the orbital s can only have this number)
ms (magnetic quantum number) = 0 (this can only be from – l to + l, the in can only be 0(
s (spin quantum number) = +1/2 or – 1/2
Answer: (4,0,0, +1/2) or (4,0,0, -1/2)