Which of the following transition metals would be expected to have the smallest atomic radius?

• A. Cu
• B. Zn
• C. Fe
• D. Mn

Answer: (B)

Verified step by step guidance

1. Recall that atomic radius generally decreases across a period from left to right in the periodic table due to increasing nuclear charge pulling electrons closer to the nucleus.
2. Identify the positions of the given transition metals (Mn, Fe, Cu, Zn) in the periodic table. They are all in the 3d series, with increasing atomic number from Mn to Zn.
3. Understand that as you move from Mn to Zn across the period, the number of protons increases, which increases the effective nuclear charge experienced by the electrons, causing the atomic radius to decrease.
4. Note that Cu and Zn are at the right end of the 3d transition metals, with Zn having a completely filled 3d subshell, which leads to a stronger effective nuclear charge and smaller atomic radius compared to Cu.
5. Conclude that among the options, Zn would have the smallest atomic radius because it is furthest to the right in the period and has the highest effective nuclear charge pulling its electrons closer.