Rank these elements according to first ionization energy..

I ranked them like this Ar Cl S P Si Al Mg Na but then it tells me that two elements should move up one spot in the ranking because of stable electrons configurations. Which ones would be moved up and why?

1 answer

Your question should have stated if you want the IP increasing or decreasing. You have ranked them decreasing because Na must be the lowest and Ar must be the highest. I expect the two closed shell elements are Al and Mg. You can look up the first IP for each at www.webelements.com