Which of these transition elements has the largest atomic radius?

Question

Quizplus · Accepted Answer

As we move from left to right across a period in the periodic table, the atomic radius generally decreases due to increasing effective nuclear charge. However, within a group, the atomic radius generally increases as we move down the group due to the addition of a new energy level. Ta (tantalum) is in the same group as Cr (chromium) and Co (cobalt), but it is located below them in the periodic table, which means it has an additional energy level compared to Cr and Co. Therefore, Ta has the largest atomic radius among the given transition elements. Re (rhenium) and Os (osmium) are in a different group, so they can be eliminated as answer choices.

Which of These Transition Elements Has the Largest Atomic Radius