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H 2 is a product of some types of anaerobic metabolism and is produced by several microorganisms, usually via reactions catalyzed by iron- or nickel-containing enzymes called hydrogenases. These enzymes catalyze the reversible redox reaction between H 2 and its component two protons and two electrons.
Hydrogen (1 H) has three naturally occurring isotopes: 1 H, 2 H, and 3 H. 1 H and 2 H are stable, while 3 H has a half-life of 12.32(2) years. [3] [nb 1] Heavier isotopes also exist; all are synthetic and have a half-life of less than 1 zeptosecond (10 −21 s). [4] [5] Of these, 5 H is the least stable, while 7 H is the most.
Liquid hydrogen (H 2 (l)) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H 2 form. [4] To exist as a liquid, H 2 must be cooled below its critical point of 33 K. However, for it to be in a fully liquid state at atmospheric pressure, H 2 needs to be cooled to 20.28 K (−252.87 °C; −423.17 °F). [5]
Depiction of a hydrogen atom showing the diameter as about twice the Bohr model radius. (Image not to scale) A hydrogen atom is an atom of the chemical element hydrogen.The electrically neutral hydrogen atom contains a nucleus of a single positively charged proton and a single negatively charged electron bound to the nucleus by the Coulomb force.
Proton: 1 H + (i.e. the cation of protium) Deuteron: 2 H +, D + Triton: 3 H +, T + In addition, the ions produced by the reaction of these cations with water as well as their hydrates are called hydrogen ions: Hydronium ion: H 3 O + Zundel cation: H 5 O 2 + (named for Georg Zundel) Eigen cation: H 9 O 4 + (or H 3 O + •3H 2 O) (named for ...
For 1 H, this amount is about 1837 / 1836 , or 1.000545, and for 2 H it is even smaller: 3671 / 3670 , or 1.0002725. The energies of electronic spectra lines for 2 H and 1 H therefore differ by the ratio of these two numbers, which is 1.000272. The wavelengths of all deuterium spectroscopic lines are shorter than the corresponding ...
High pressure electrolysis is the electrolysis of water by decomposition of water (H 2 O) into oxygen (O 2) and hydrogen gas (H 2) by means of an electric current being passed through the water. The difference with a standard electrolyzer is the compressed hydrogen output around 120–200 bar (1740–2900 psi, 12–20 MPa). [146]
The hydrogen cycle consists of hydrogen exchanges between biotic (living) and abiotic (non-living) sources and sinks of hydrogen-containing compounds. Hydrogen (H) is the most abundant element in the universe. [1] On Earth, common H-containing inorganic molecules include water (H 2 O), hydrogen gas (H 2), hydrogen sulfide (H 2 S), and ammonia ...