Question

Which group of atoms have nearly the same atomic radius ?

• A. Na, K, Rb, Cs,
• B. Li, Be, B, C
• C. Fe, Co, Ni
• D. F, Cl, Br, I

Answer 1

Answer: (C)

Fe, Co, Ni

Fe, Co and Ni are transition metals in the same period where the atomic radii do not vary much. This is due to the extra screening by the 3d electrons which offset the increasing pull by the additional protons going from Fe to Co and Ni on the outer 4s electrons.