Question

Na,Mg and Al are the elements of the 3rd period of modern periodic table having group number 1,2 and 13 respectively .which one of the which one of these elements has the (a)highest valency,(b) the largest atomic radius and(C) Maxwell chemical reactivity justify your answer starting the reasons for each

Answer 1

Aluminium (Al) has the highest valency. Valency of Na is 1, Mg is 2, Al is 3.

Na has the largest atomic radius. As we move from left to right in a period, the atomic radius decreases as increase in nuclear charge pulls the electrons closer to the nucleus reducing the atomic size.
Na has the maximum chemical reactivity. Reactivity decreases on moving from left to right in a period.

Answer 2

(a) Al has the highest valency
(b) Na has the largest atomic radius
(c) Na has highest chemical reactivity because reactivity decreaes as we move left to right in period.