Question

Which is the most active group of nonmetals?

Answer 1

Periodic table has eighteen groups and seven periods, all the groups are mainly classified as blocks. We have four blocks in the periodic table: s-block, p-block, d-block and f-block. First two groups are under s-block (alkali metals, alkaline earth metals) third to twelve are in d-block(transition metals), thirteen to eighteen in p-block, f-block are inner transition metals.

Complete answer:
Non-metals in periodic tables are present right to periodic tables. Group thirteen to eighteen also known as p-block elements. Group seventeen is the most active group among non-metals. The first element of this group is Fluorine (F) followed by chlorine (Cl), bromine (B), iodine (I) and astatine (At).
This group is known as the halogen family as the salts of these elements are present in seawater. The reactivity of halogens is due to their low bond dissociation energy, high enthalpy of hydration, high electron affinity. Many compounds of these elements are used in our daily lives. As they are very reactive, they are never found in native state in nature. They are present in many oxidation states.
Some essential compounds from this group are: HCl, NaCl, HBr etc.

Note:
Fluorine is the most electronegative element and it has some different properties from its group members. This is known as anomalous behavior which is due to very small size, low bond dissociation energy, high electronegativity, non-availability of d-orbitals in valence shell. And also fluorine is the strongest oxidizing agent.