Question

what do you mean by the valency of the elements according to the periods and Groups​

Answer 1

valency means the atoms which are required to remove or added in any element to be stable or to complete octet state also it is combining capacity of an element..in group valence shell increases among elements but valency remains same.but in period , valency increases but all elements have same number of valence shell,thank you

Answer 2

Answer:

for metals, it is their valency electrons. for non-metals, it is the no. needed for it to have a stable octet.

Explanation:

this is because metals lose electrons in a chemical reaction to have a stable octet. on the other hand, non-metals gain those lost electrons to have afull valency shell (or stable octet)