Question

1- Give the electron configurations of the following species:
He, C, O, O 2-, F -, Ne, Na+, Al, Cl, Ca, Cr, Fe, and Cu
which of the above species are isoelectronic, that is those with the same configuration?

2- What are the allowable spins, m s ?

3- How many lines are observed in the visible atomic line spectrum for the H atom