Hydrogen

Hydrogen (H) is the lightest element in the periodic table with a standard atomic weight of 1.008. Touted as the most abundant chemical element in the universe, it is said to make up 75 percent of normal matter by mass and more than 90 percent by number of atoms. At standard temperature and pressure, hydrogen is a colorless, odorless, tasteless, non-toxic, nonmetallic, highly combustible gas (The sun is 75 percent hydrogen and nearly 25 percent helium with a few extra elements thrown in.) Most of the hydrogen on earth exists in molecular forms such as water or organic compounds. Hydrogen is considered to function as a “bonding element” in many cases. Hydrogen bonding occurs between a hydrogen atom and an electronegative atom such as oxygen, fluorine, and chlorine.