Question

determine where on the periodic table you find the elements with the largest atomic radius.
i need a hint
the elements with a large radius are all in period 7 (the row at the bottom of the periodic table).
the elements with a large radius are all in group 1 (the column at the left of the periodic table).
the elements with a large radius are all in group 18 (the column at the right of the periodic table).
the elements with a large radius are all in period 1 (the row at the top of the periodic table).

Explanation:

Atomic radius increases down a group (due to more electron shells) and decreases across a period (due to increasing nuclear charge pulling electrons closer). Group 1 has elements with one valence electron. As we go down group 1, the number of electron shells increases. Period 7 has many heavy - element synthetic elements which are not the largest in terms of atomic radius in a general sense compared to group 1 elements. Group 18 (noble gases) have relatively smaller atomic radii (van der Waals radii which are smaller than metallic or covalent radii for comparable elements). Period 1 has only two elements (H and He) which have very small atomic radii.

Answer:

The elements with a large radius are all in group 1 (the column at the left of the periodic table).