Periodicity is observed due to similar ………. (number of valence electrons/atomic number/electronic configuration)

How does the electronic configuration in atoms change

(i) in a period from left to right?

(ii) in a group from top to bottom?

Elements of group 1 and elements of group 17 both have valency 1. Explain.

Correct the statements.

(i) Elements in the same period have the same valency.

(ii) Valency depends upon the number of shells in an atom.

(iii) Copper and zinc are representative elements.

(iv) Transition elements are placed at extreme right of the periodic table.