In general, the reactivity of the element decreases from top to bottom in a group except `IA` and `IIA`. In these groups it increases. While in the period on moving left to right no such decrease or increase are observed.

In case of metals generally the reactivity increases with decrease in ionization energy, so on moving left to right in a period `I.E.` increases, then the reactivity of metal decreases. In case of non-metals the reactivity is proportional to Electronegativity & electron affinity so it increases in a period from left to right but decreases in a group from top to bottom.