Explanation

• Strontium has the largest metallic radius with a value of 215 pm (picometers).
• This is due to its position in the periodic table, as it is a heavy alkaline earth metal with a large atomic radius.

Here are the atomic radii of the elements you've listed:

• Strontium (Sr): 215 pm
• Calcium (Ca): 197 pm
• Magnesium (Mg): 160 pm
• Beryllium (Be): 125 pm