Question

explain the gradation in reactivity of
halogen family in modern periodic table

Answer 1

1) As we go down the group, the electron affinity of the element decreases. So the reactivity decreases as we go down the group. So fluorine is the most reactive among the halogens.

2) Common properties of the halogen group are

They have high electron affinity, ionization enthalpy and electronegativity. They are the most non metallic as well as very good oxidizing agents.

3) Elements in group zero has the valency zero as they have eight electrons in their outermost shell with no further reason to react as per octet rule.

Hence they are called inert gases.