Final answer:
To locate the element with the largest atomic radius on the periodic table, one should move in the downward and leftward direction, as atomic radii decrease from left to right across a row and increase from top to bottom down a column. Option D is correct.
Step-by-step explanation:
If you wanted to find the element with the biggest radius on the periodic table, you would move in the downward and leftward direction. This trend occurs because atomic radii decrease as you go from left to right across a row, and they increase as you go down a column. As a result, the largest atoms are located in the lower left corner of the periodic table, and the smallest are in the upper right corner.
For example, within a group (also known as a column), as the atomic number increases, so does the principal quantum number, which means that the valence electron shell lies farther from the nucleus, leading to a larger atomic radius. Conversely, from left to right across a period (row), the effective nuclear charge increases as electrons are added to the same shell, which draws the electron cloud closer, causing the atomic radius to decrease. Therefore, the correct direction to find the element with the largest atomic radius is Down (D).