Hydrogen

Hydrogen, the lightest and most abundant element in the universe, is a gas at standard conditions with the molecular formula H2. Colorless, odorless, and highly flammable, hydrogen makes up about 75% of all normal matter. It is found in stars like the Sun, where it exists as plasma, and on Earth in water, organic compounds, and other molecules. The most common hydrogen isotope (1H) has one proton and electron but no neutrons.