Which of the following correctly distinguishes the element iron (Fe) from nickel (Ni) on the periodic table?

• A. Iron (Fe) has a lower atomic number than nickel (Ni).
• B. Iron (Fe) has a higher atomic mass than nickel (Ni).
• C. Iron (Fe) is located in Group 1, while nickel (Ni) is in Group 2.
• D. Iron (Fe) is a nonmetal, while nickel (Ni) is a metal.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand that elements on the periodic table are primarily distinguished by their atomic number, which is the number of protons in the nucleus of an atom of that element.
2. Step 2: Recall that iron (Fe) has an atomic number of 26, and nickel (Ni) has an atomic number of 28, meaning iron has fewer protons than nickel.
3. Step 3: Recognize that atomic mass generally increases with atomic number, but there can be exceptions due to isotopic abundance; however, atomic number is the definitive way to distinguish elements.
4. Step 4: Note that both iron and nickel are transition metals and are located in the same block of the periodic table, so they are not in Group 1 or Group 2, which are the alkali and alkaline earth metals respectively.
5. Step 5: Understand that both iron and nickel are metals, so the statement that iron is a nonmetal while nickel is a metal is incorrect.