Which Element Has the Smallest Atoms?

The element with the smallest atomic mass is hydrogen (H), which is made up of protons and electrons, two types of subatomic particles. A smaller atomic radius is expected as we continue moving right along the period. When you go down the group, you notice that the atomic radius gets bigger and bigger. There are only two elements in existence that have less than 100 protons each.

As the first element in the noble gas group, it is a non-toxic, non-odouring and non-tasting gas that does not have any atomic structure whatsoever. Unlike any other element in the periodic table, it has the lowest boiling point. The second most prevalent and second lightest element in the universe is helium.