In the periodic table, there is a size trend.
The trend occurs horizontally and vertically on the table.
- From right to left, the atomic radius gets larger.
- From top to bottom, the atomic radius gets larger.
The reasoning for this is the additional energy levels and electrons being added as you go from right to left or top to bottom.
We can see that Magnesium is higher and more right in the periodic table than sodium and calcium.
Thus, Magnesium has a smaller atomic radius than both sodium and calcium
