Atoms with the largest atomic radius can be found in the bottom left corner of the periodic table. As you move down a group (column), the atomic radius increases due to the addition of electron shells. Additionally, as you move from right to left across a period (row), the atomic radius also increases because there is less positive charge in the nucleus pulling the electrons closer.
For example, cesium (Cs), found in Group 1 (alkali metals) and in Period 6, has one of the largest atomic radii on the periodic table. Other elements with large atomic radii include rubidium (Rb) and potassium (K), which are also in Group 1 but higher up in the periodic table.