【Daily Question】Theoretical Foundation 2020.06.27
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Multiple-choice question: An element has a maximum oxidation state of +6; the hydrates of its oxides are strong acids, and its atomic radius is the smallest among elements in the same group. Which element is this? (A) Mn (B) Cr (C) Mo (D) S. Answer: B. Hint: Those who can explain the solution process will receive an additional reward; the answer can be found in the response
The valence electron configuration of B Mn is 3d54s2; the valence electron configuration of Cr is 3d54s1; the valence electron configuration of Mo is 4d55s1; the valence electron configuration of S is 3S23p4. The highest oxidation state is +6, indicating that there are a total of 6 electrons in the valence electron configuration. Moreover, its atomic radius is the smallest among elements in the same group, which shows that this element occupies the top position in that group. Only Cr meets these criteria. Answer: B
B. Analysis of option A: Manganese belongs to the seventh transition series, and its highest oxidation state is +7； Options BC all belong to Group 6; the highest value is +6, and B has the smallest radius within the same group. Group D belongs to the sixth main group; its highest oxidation state is +6. However, it does not have the smallest radius among elements of the same group – oxygen has the smallest radius