Question

How does number of (i) valence electrons (ii) valency vary on moving from left to right : (i) in the second period of a periodic table (b) in the third period of a periodic table

Answer 1

Valence electrons increase on moving left to right in a period and remain same in a group..

Valency increases for the first 4 elements and then decrease to the next 4 elements in a period (moving left to right)..

U don't need to specify in a particular period.. it is because all periods have the same characteristics..
That's how it is designed by "HENRY MOSELEY"..