To determine which element has the smallest atomic radius among Neon (Ne), Argon (Ar), Krypton (Kr), and Xenon (Xe), we need to consider their positions on the periodic table and the trends in atomic radii.
1. Periodic Trends:
- Across a Period: The atomic radius decreases as you move from left to right across a period. This is because, within a period, the number of protons increases, which increases the positive charge of the nucleus. This greater positive charge pulls the electron cloud closer to the nucleus, resulting in a smaller atomic radius.
- Down a Group: The atomic radius increases as you move down a group. This happens because each subsequent element has an additional electron shell, which increases the radius despite the increasing nuclear charge.
2. Element Positions:
- Neon (Ne): Located in Period 2, Group 18.
- Argon (Ar): Located in Period 3, Group 18.
- Krypton (Kr): Located in Period 4, Group 18.
- Xenon (Xe): Located in Period 5, Group 18.
Neon is at the top of Group 18 and is in the second period, whereas Argon, Krypton, and Xenon are lower down in the same group and belong to later periods.
Given these periodic trends:
- Neon, being at the top of Group 18 and in the second period, will have fewer electron shells compared to Argon, Krypton, and Xenon.
- Thus, Neon will have the smallest atomic radius among the given elements since it has fewer electron shells and the increased nuclear charge will pull the electrons more tightly towards the nucleus.
Conclusion:
The element with the smallest atomic radius among the given options is Neon (Ne).
