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Hydrogen is a chemical element; it has symbol H and atomic number 1. It is the lightest element and, at standard conditions, is a gas of diatomic molecules with the formula H 2, sometimes called dihydrogen, [11] hydrogen gas, molecular hydrogen, or simply hydrogen. It is colorless, odorless, [12] non-toxic, and highly combustible.
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 ...
Examples include iron, essential to hemoglobin; and magnesium, essential to chlorophyll. Some elements are essential only to certain taxonomic groups of organisms, particularly the prokaryotes. For instance, the lanthanide series rare earths are essential for methanogens. As shown in the following table, there is strong evidence that 19 of the ...
Biological hydrogen production is also observed in nitrogen-fixing cyanobacteria. This microorganisms can grow forming filaments. This microorganisms can grow forming filaments. Under nitrogen-limited conditions some cells can specialize and form heterocysts , which ensures an anaerobic intracellular space to ease N 2 fixation by the ...
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.
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 single positively charged proton in the nucleus, and a single negatively charged electron bound to the nucleus by the Coulomb force.
None of President-elect Trump's Cabinet nominees can be confirmed until he takes office on Jan. 20 – and expect a traffic jam in the Senate when he does.
Pure water is an example of a chemical substance, with a constant composition of two hydrogen atoms bonded to a single oxygen atom (i.e. H 2 O). The atomic ratio of hydrogen to oxygen is always 2:1 in every molecule of water. Pure water will tend to boil near 100 °C