Which group in the periodic table contains elements with the smallest atomic radius?

• A. Group 18 (Noble gases)
• B. Group 2 (Alkaline earth metals)
• C. Group 1 (Alkali metals)
• D. Group 17 (Halogens)

Answer: (A)

Verified step by step guidance

1. Understand that atomic radius generally decreases across a period (left to right) in the periodic table due to increasing nuclear charge pulling electrons closer to the nucleus.
2. Recognize that atomic radius generally increases down a group because additional electron shells are added, making the atom larger.
3. Identify the groups mentioned: Group 1 (Alkali metals) are on the far left, Group 2 (Alkaline earth metals) are next to them, Group 17 (Halogens) are near the right, and Group 18 (Noble gases) are at the far right of the periodic table.
4. Apply the trend that elements in Group 18 have the smallest atomic radius in their respective periods because they have the highest effective nuclear charge without adding extra electron shells compared to other groups in the same period.
5. Conclude that among the given options, Group 18 (Noble gases) contains elements with the smallest atomic radius.