Question

What do you understand by valency write their priodicity ?​

Answer 1

Explanation:

As the is periodicity across the group so valency will be the same for all elements present in the group

Answer 2

Answer:

the valence or valency of an element is a measure of its combining power with other atoms when it forms chemical compounds or molecules. The concept of valence was developed in the second half of the 19th century and helped successfully explain the molecular structure of inorganic and organic compounds.