Hydrogen is the lightest, simplest, and most abundant element in the universe, but it is very scarce on Earth in its elemental form. Hydrogen fusion is the phenomenon that powers most stars, and is also a potential source of energy for generating electricity on Earth.Continue Reading
Hydrogen makes up approximately 90% of all visible matter in the universe. Its ordinary form consists of one proton and one electron, but there exist two isotopes named deuterium and tritium that also contain one or two neutrons, respectively. On Earth, hydrogen is naturally found as a diatomic molecule, consisting of two hydrogen atoms chemically bound together.
Molecular hydrogen boils at only 20.4 degrees Celsius above absolute zero, so liquid hydrogen is very cold. It is also very flammable and is used as a component in the fuel for many modern rockets used in space exploration. Hydrogen gas is very rare on Earth because the atoms are so light. Hydrogen atoms in the atmosphere move at an average of 16.2 kilometers per second, whereas they only need to move at 11.2 kilometers per second to escape from the Earth's gravitational pull. Therefore, most hydrogen on Earth today is in the form of hydrogen containing compounds such as hydrocarbons and water.
Approximately 9.5% of the human body consists of hydrogen, by weight.Learn more about Chemistry