How does the valency of elements vary in going down a group of the periodic table ?

How does the number of valence electrons vary on moving from left to right :

(i) in the first period of the periodic table ?

(ii) in the second period of the periodic table

How does the valency of elements change on moving from left to right in the third period of the periodic table ?

Name the element which is in :

(a) first group and third period

(b) seventeenth group and second period.

How do electronic configurations of elements change in second period of periodic table with increase in atomic numbers ?