Solution:
The third period of the modern periodic table contains 8 elements.The 8 elements are sodium, magnesium, aluminium, silicon, phosphorus, sulphur, chlorine and argon. The first two, sodium and magnesium, are members of the s-block of the periodic table, while the others are members of the p-block. Argon is a noble gas that does not participate in the reaction. Along the period, the atomic radius decreases.
