Browse Questions

# Rank the elements in each of the following sets in order of decreasing First Ionization Energy IE$_1$: Kr, He, Ar

Can you answer this question?

Answer: He > Ar > Kr
IE decreases as you proceed down in a group; IE increases as you go across a period.
These three elements are all in Group 8A(18), IE decreases down a group.
answered Jul 23, 2014