Hydrogen

Hydrogen is the first element in the periodic table. Its Chemical symbol|symbol is H. It is the lightest element having only one proton and one electron. Hydrogen has three naturally occuring isotopes: 1H, known as protium is the most common by far, 2H is called deuterium, and 3H is called tritium. Hydrogen is the only element whose isotopes are given unique names - all other isotopes are simply named after their element, for example 14C is simply called carbon fourteen.

Pure hydrogen is a diatomic gas that is quite flammable. Because the combustion of hydrogen produces only water, it has gained attention as a non-polluting fuel for engines, especially in automobiles.