Question

5% of the universe is this type of "ordinary matter" made up of atoms

Answer 1

The "ordinary matter" you are referring to is often called baryonic matter, which consists primarily of protons, neutrons, and electrons. This type of matter is what makes up stars, planets, galaxies, and all living things. In the context of the universe's composition, approximately 5% of the total energy density of the universe is made up of this ordinary matter. The remainder of the universe is thought to consist of dark matter (about 27%) and dark energy (about 68%).