2. A colorless, highly flammable gaseous element, the lightest of all gases and the most abundant element in the universe, used in the production of synthetic ammonia and methanol, in petroleum refining, in the hydrogenation of organic materials, as a reducing atmosphere, in oxyhydrogen torches, and in rocket fuels.
3. From 1791, French hydrogène, coined in 1787 by G. de Morveau from Greek hydr-, stem of hydros, "water" + French -gène, "producing". So called because it forms water when exposed to oxygen.
Source: water, most organic compounds. Use: industrial processes, production of ammonia, reduction of metal ores to metals.
The hydrogen nucleus is made up of a particle carrying a unit positive electric charge, called a proton.
Because the bare nucleus can readily combine with other particles (electrons, atoms, and molecules), the isolated hydrogen ion can exist only in a nearly particle-free space (high vacuum) and in the gaseous state.
In common usage, the term hydrogen ion is used to refer to the hydrogen ion present in water solutions, in which it exists as the combined molecule H + H2O.
The amount of hydrogen ion present in a water solution is used as a measure of the acidity of a substance; the higher the concentration of hydrogen ion the more acidic the solution and the lower the pH.
Power from wind or photovoltaic systems would drive photo-electrolytic hydrogen production.