The periodic trend of reactivity depends on whether the elements are metals or nonmetals. For metals, reactivity increases down a group and from right to left across a period. Nonmetals do the opposite. For nonmetals, reactivity increases up a group and from left to right across a period. Therefore, the rank is as follows:
Fluorine
Selenium
Neon
Hope this answers the question. Have a nice day.
K. Ionization energy increases as you go up and to the right, and k is the furthest left and furthest down
