For the isoelectronic series S2-, Cl-, Ar, K+, and Sc3+, which species requires the least energy to remove an outer electron?

Question

thanks

They all have the same number of electrons (40) in the same shell arrangements, but S(2-) has the least nuclear charge. That should be a clue. Furthermore, doubly negative ions (with two extra electrons) tend to be quite unstable.

That number of electrons I wrote should be 18, not 40.

oh, that clears it up a bit, thanks!

Answer 1

sc3+