Hydrogen is a colorless, odorless, tasteless, non-toxic, nonmetallic, highly combustible diatomic gas with the molecular formula H2. The most common isotope of hydrogen, termed protium, has one proton and no neutrons. It is the most abundant chemical substance in the universe, constituting roughly 75% of all baryonic mass.
About Hydrogen in brief
Hydrogen is a colorless, odorless, tasteless, non-toxic, nonmetallic, highly combustible diatomic gas with the molecular formula H2. The most common isotope of hydrogen, termed protium, has one proton and no neutrons. Hydrogen gas was first artificially produced in the early 16th century by the reaction of acids on metals. In 1766–81, Henry Cavendish was the first to recognize that hydrogen gas was a discrete substance, and that it produces water when burned. Most hydrogen is used near the site of its production, the two largest uses being fossil fuel processing and ammonia production, mostly for the fertilizer market. The detection of a burning hydrogen leak may require a flame detector; such leaks can be very dangerous. Pure hydrogen-oxygen flames emit ultraviolet light and with high oxygen mix are nearly invisible to the naked eye, as illustrated by the faint plume of the Space Shuttle Main Engine, compared to the highly visible plumes of a Space Shuttle Solid Rocket Booster. The ground state energy level of a hydrogen atom in 6eV is roughly 613.eV, which is roughly equivalent to the absence of an ultraviolet photon of 91 nm wavelength. The Bohr model of the atom can only occupy certain distances from the proton, therefore only certain mechanical energies are allowed from the atom. A more accurate description of the hydrogen atom comes from a purely mechanical description of hydrogen from a quantum mechanics model. Because the electron and proton are held together by gravity, planets and planets are held by gravity of the discretization of the planets and stars, the model of hydrogen comes from the theory of quantum mechanics postulated by Bohr in early quantum mechanics.
The hydrogen atom is the only neutral atom for which the Schrödinger equation can be solved analytically, and has played a key role in the development of quantum Mechanics. It is the most abundant chemical substance in the universe, constituting roughly 75% of all baryonic mass. It can take the form of a negative charge when it is known as a hydride, or as a positively charged species denoted by the symbol H+. It spontaneously reacts with chlorine and fluorine to form hydrogen chloride and hydrogen fluoride, respectively. H2 is relatively unreactive. The thermodynamic basis of this low reactivity is the very strong H-H bond, with a bond dissociation energy of 435. 7 kJmol. It forms explosive mixtures with air in concentrations from 4–74% and with chlorine at 5–95%. The explosive reactions may be triggered by spark, heat, or sunlight. The hydrogen autoignition temperature, the temperature of spontaneous ignition in air, is 500 °C. The visible orange flames in the Hindenburg airship was a notorious example of hydrogen combustion and the cause is still debated. Hydrogen plays a particularly important role in acid–base reactions because most acid-base reactions involve the exchange of protons between soluble molecules.