Na, Mg, and A1 are the elements having one, two and three valence electrons respectively. Which of these elements

Na, Mg, and A1 are the elements having one, two and three valence electrons respectively. Which of these elements
(i) has the largest atomic radius,
(ii) is least reactive? Justify your answer stating reason for each.

(i) Na has the largest atomic radius compared to Mg and Al. These elements belongs to
same third period.
Reason: The atomic radius decreases when moving from left to right along a period. This is due to an increase in nuclear charge which tends to pull the electrons closer to the nucleus and reduces the size of the atom.

(ii) Al is least reactive.
Reason: Al is smaller in size compared to Na and Mg. so it has lesser tendency to lose electrons due to high effective nuclear charge.