Periodic Trends and Atomic Properties (4E) Practice Test

In a study of ion channel selectivity, researchers compare dehydrated ionic radii as a factor in permeation through a narrow pore. They consider the common biological cations Na+, Mg2+, K+, and Ca2+. Based on periodic trends and effective nuclear charge, which ion is expected to have the smallest ionic radius?

Assume typical oxidation states shown.

A protein engineering lab is evaluating metal cofactors that coordinate to carboxylate side chains. They compare Mg2+ and Ca2+ and note different binding strengths attributed partly to ionic size. Based on periodic trends, which statement is most consistent?

Consider Mg and Ca in Group 2.