Evaluation Methods. Several studies from around the world that have evaluated Incredible Years components meet the Promising Practices Network (PPN) criteria and have found Incredible Years to be a promising or proven program. These studies are listed below, by the component that was tested in the study.
The noble gases (arranged in order of increasing atomic weight) are helium, neon, argon, krypton, xenon and radon. Helium, neon and argon are the three noble gases with the lowest atomic masses. Helium, Neon, Argon. Helium, neon, and argon are the three lightest members of the noble  gases. Hydrogen is the lightest of all elements. According to the Periodic  Table, its atomic weight is 1.00794 u, even lighter than helium.
Hydrogen HYDROGEN is a chemical element with symbol H and atomic number 1. With a standard atomic weight of circa 7000100800000000000â 1.008, hydrogen is the lightest element on the periodic table . Its monatomic form (H) is the most abundant chemical substance in the Universe, constituting roughly 75% of all baryonic mass.