The element with an atomic number of one on the periodic table is hydrogen (H). Hydrogen is the lightest and simplest element, consisting of a single proton in its nucleus and an electron orbiting around it. It is the most abundant element in the universe and plays a crucial role in the formation of stars and the production of energy through nuclear fusion. Hydrogen has various applications, including its use as a fuel, a reducing agent in industrial processes, and a component of compounds such as water and organic molecules.