Question

put these elements in order of smallest to largest atomic radius xenon neon radon argon krypton helium

Explanation:

Step1: Recall atomic - radius trend

Atomic radius increases down a group in the periodic table. These elements (helium, neon, argon, krypton, xenon, radon) are all noble gases in Group 18.

Step2: Order elements

As we move down Group 18, the atomic radius increases. So, the order from smallest to largest atomic radius is based on their position in the group.

Answer:

Helium, Neon, Argon, Krypton, Xenon, Radon