MCAT General Chemistry Question 16: Answer and Explanation

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Question: 16

1. Lithium and sodium have similar chemical properties. For example, both can form ionic bonds with chloride. Which of the following best explains this similarity?

  • A. Both lithium and sodium ions are positively charged.
  • B. Lithium and sodium are in the same group of the Periodic Table.
  • C. Lithium and sodium are in the same period of the Periodic Table.
  • D. Both lithium and sodium have low atomic weights.

Correct Answer: B

Explanation:

The Periodic Table is organized into periods (rows) and groups (columns). Groups (columns) are particularly significant because they represent sets of elements with the same valence electron configuration, which in turn will dictate many of the chemical properties of those elements. Although choice (A) is true, the fact that both ions are positively charged does not explain the similarity in chemical properties; most metals produce positively charged ions. Choice (C) is not true because lithium and sodium are in the same group, not period. Finally, although lithium and sodium do have relatively low atomic weights, so do several other elements that do not share the same properties, eliminating choice (D).

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