The chemical element with the atomic number 1 is hydrogen. As the simplest and most abundant element in the universe, hydrogen consists of just one proton and one electron. It is a colorless, odorless gas at room temperature and exists primarily as diatomic molecules (H2). Hydrogen plays a crucial role in various chemical reactions, including those that power stars like our Sun through nuclear fusion. Furthermore, hydrogen is a fundamental building block of organic compounds and essential for life on Earth. It is also being explored as a potential clean energy source in fuel cells and other technologies.