Question

which group or period of elements has the largest atomic radius

Answer 1

The atomic radius generally increases from top to bottom within a group in the periodic table. Therefore, the group or period of elements that has the largest atomic radius is the bottommost group in the periodic table, known as Group 1 (alkali metals) or Group 2 (alkaline earth metals). This is due to the addition of new energy levels (shells) as you move down the group, increasing the overall size of the atom.