The elements in which of the following groups have most nearly the same atomic radius?

• A. Elements in the same period
• B. Elements with consecutive atomic numbers
• C. Elements in the same group
• D. Elements in the same transition series

Answer: (D)

Verified step by step guidance

1. Recall that atomic radius generally changes in a predictable way across the periodic table: it decreases from left to right across a period and increases from top to bottom down a group.
2. Understand that elements in the same period have different atomic radii because the number of protons increases, pulling electrons closer and reducing size.
3. Recognize that elements with consecutive atomic numbers are neighbors in the periodic table and usually have noticeably different atomic radii due to changes in nuclear charge and electron configuration.
4. Note that elements in the same group have similar outer electron configurations, but atomic radius increases significantly down the group because new electron shells are added.
5. Focus on the transition series: elements in the same transition series have electrons being added to inner d-subshells, which shield the outer electrons less effectively, causing their atomic radii to remain relatively constant across the series.