Answer:
Sodium (largest) and Sulfur (smallest)
Explanation:
Atomic radius of an element/atom is the distance between the central nucleus of the element/atom and the outermost shell of electrons. This indicates that the higher the number of shells, the higher the atomic radius, hence atomic radius increases down the group.
But the question focuses on elements in the same period. Magnesium (Mg), Silicon (Si), Sulfur (S) and Sodium (Na) are all found in period 3 on the periodic table. Elements having the same number of electron shells are found in the same period but the number of valence electrons plays a crucial role in atomic radius across a period - this is because the outermost shell is easily attracted to the central nucelus when there are fewer number of valence electrons on it, hence atomic radius decreases across the period as there is an increase in valence electrons across the period.
The trend below shows increasing pattern of atomic radius of the options provided
S< Si< Mg< Na
The trend shows that sulfur (S) has the smallest while sodium (Na) has the largest atomic radius.
