(a) State the modern periodic law.

(b) How many periods and groups are there in the modern periodic table?

What is the main characteristic of the last element in each period of the Periodic Table? What is the general name of such elements?

From the standpoint of atomic structure, what determines which element will be the first and which the last in a period of the periodic table ?

(a) What are the following groups known as?

1. Group 1
2. Group 17
3. Group 18

(b) Name two elements of each group.