How much of the matter in the universe is comprised of atoms?

4.6%.

Explanation:

Actually, the belief before few decades ago is that the whole of the universe comprises of atoms, you, me, stars and so on comprises of atoms that is protons, neutrons and electrons but now according to some researches made, the whole of the universe does not contain atoms naturally as their are some unseen things in the universe. According to the researches by astrophysicists the universe contains about 4.6 percent atoms and the others are dark energy which has the largest portion of the universe of about 71.4 percent and cold dark matter which contains about 24 Percent of the universe.

Atoms are the components of ordinary matter, also called baryonic matter, which only represents 4% of the universe, while the remaining 96% would be formed by what is known as dark matter and dark energy which constitute two of the unsolved problems in physics.