Which element in Group 8 (the 8th column) of the periodic table has the largest atomic radius?

• A. Os (osmium)
• B. Ru (ruthenium)
• C. Fe (iron)
• D. Hs (hassium)

Answer: (A)

Verified step by step guidance

1. Identify the elements listed and confirm they belong to Group 8 of the periodic table: Fe (iron), Ru (ruthenium), Os (osmium), and Hs (hassium).
2. Recall that atomic radius generally decreases across a period (left to right) and increases down a group (top to bottom) due to the addition of electron shells.
3. Since all these elements are in the same group (Group 8), compare their positions vertically: Fe is in period 4, Ru in period 5, Os in period 6, and Hs in period 7.
4. Understand that as you move down the group from Fe to Hs, the atomic radius tends to increase because each element has an additional electron shell compared to the one above it.
5. Consider relativistic effects and electron shielding, which can slightly affect atomic radius for very heavy elements like Hs, but generally, Os (period 6) will have a larger atomic radius than Fe and Ru, and Hs (period 7) might have a smaller radius than expected due to these effects.