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

How does the valency of elements vary a) in going down a group b) in going from left to right in a period of the periodic table.

(a) How does the electropositive character of elements change on going down in a group of the periodic table? (b) State how the valency of elements varies (i) in a group and (ii) in a period, of the periodic table.

What happens to number of valence electrons in atoms of elements as we go down a group of the periodic table ?

(a) How does the chemical reactiviyt of alkali metals vary on going down in group 1 of the periodic table? (b) How does the chemical reactivity of the halogens vary on going down in group 17 of the periodic table?

How does the basicity of the oxides of representative elements vary on moving down a group in the periodic table? On moving across a period from left to right, how does the acidicty of the oxides of representative elements vary?

What is long form periodic table ? How do the properties of elements vary in groups and periods of the periodic table? Name the elements of zero group.

How does valency change within a group of the periodic table?