Noble gases mark the end of every period in the long form of the periodic table. What is the atomic — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

The noble gases occur at the end of periods 1, 2, 3, 4, etc. The first is $He$ ($Z=2$). The second is $Ne$ ($Z=10$). The third is $Ar$ ($Z=18$). The fourth is $Kr$ ($Z=36$).