Hydrogen, designated as h on the periodic table of the elements, is the simplest and most abundant of all the elements. A hydrogen atom consists of a single proton and an electron, and has the lowest density of all known matter. Hydrogen molecules combine to form a stable molecule of two hydrogen atoms and their associated electrons.

Hydrogen is an odorless, colorless, tasteless gas (H2) that is not very reactive at ordinary temperature levels. It burns with a very hot, almost invisible flame, and can be used as a fuel in nuclear fusion and by chemical reactions. Nuclear fusion occurs with Deuterium combining at the proton level to form helium.

Hydrogen comprises most of the matter in the sun, which generates light by a process of nuclear ...