reactivity determined by an elements

Answer 1

The reactivity of elements is determined by the number of valence elctrons in their outermost energy shell.

There are 8 groups of elements on the periodic table in which the number of valence electrons can be counted on. The fewer the valences electrons in the group the more reactive the elements in the group. The last group,on the far right end, the Noble gases, have 8 valence electrons and are considered inert.(non-reactive) The first group on the far left of the periodic table, the alkali earth metals have one valence electon and are the most reactive of elements.