The lightest element on the periodic table is hydrogen. With the atomic number 1, hydrogen consists of only one proton and one electron, making it the simplest and most abundant element in the universe. Hydrogen exists primarily as a gas at standard temperature and pressure and is known for its flammability. It plays a vital role in various chemical processes, including combustion and the formation of water when combined with oxygen. In addition to its significance in chemistry, hydrogen is a key component of stars, including our sun, where it undergoes nuclear fusion, producing energy that sustains life on Earth.