which element has the smallest atomic radius?\nmagnesium, mg\nsodium, na\naluminum, al

Explanation:

Step1: Locate the elements in the periodic table.

Sodium (Na), Magnesium (Mg), and Aluminum (Al) are all located in Period 3 of the periodic table. Na is in Group 1, Mg is in Group 2, and Al is in Group 13.

Step2: Identify the trend for atomic radius across a period.

Atomic radius generally decreases as you move from left to right across a period in the periodic table. This is due to the increasing effective nuclear charge pulling the electron shells closer to the nucleus.

Step3: Apply the trend to the given elements.

Since Na, Mg, and Al are in the same period (Period 3), and their positions from left to right are Na, Mg, Al, the atomic radius decreases in this order: $Radius_{Na} > Radius_{Mg} > Radius_{Al}$.

Step4: Determine the element with the smallest atomic radius.

Based on the trend, Aluminum (Al), being the rightmost element among the three in Period 3, has the smallest atomic radius.

Answer:

aluminum, Al