Question

Which element have more atomic radius sodium magnesium aluminium?

Answer 1

sodium have more atomic radius from left to right in group atomic size dicreases due to increase in nuclear charge

Answer 2

You see the size of the atom decreases as we move from left to right in a period.

So observe the 3rd period .From left to right first comes sodium, then magnesium and then aluminum.

So it is clear that sodium has the largest atomic radius among three.

Even you can compare the Van der Waals radius

Sodium --- 227 picometer

Magnesium --- 220 picometer

Aluminum --- 143 picometer

So from here also you can get,

Na > Mg > Al