The universe is composed of a vast variety of atoms. An atom is the basic unit of matter and consists of a nucleus, which contains protons and neutrons, surrounded by electrons orbiting the nucleus.
While there are over a hundred known elements, each with its unique set of atoms, the most common elements in the universe are hydrogen and helium. These two elements make up the majority of the observable matter in the universe, particularly in the form of gas clouds and stars. Hydrogen is the simplest atom, consisting of just one proton and one electron, while helium has two protons, two neutrons, and two electrons.
However, beyond hydrogen and helium, there are numerous other elements that contribute to the diversity of atoms in the universe. Elements like carbon, oxygen, nitrogen, and iron are essential for the formation of more complex structures, including planets, organic compounds, and life as we know it.
So, while hydrogen and helium dominate in terms of abundance, the universe is not made up of just one type of atom. The presence of different elements and their combinations is what allows for the complexity and diversity we observe in the cosmos.