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  2. Hydrogen - Wikipedia

    en.wikipedia.org/wiki/Hydrogen

    By some definitions, "organic" compounds are only required to contain carbon. However, most of them also contain hydrogen, and because it is the carbon-hydrogen bond that gives this class of compounds most of its particular chemical characteristics, carbon-hydrogen bonds are required in some definitions of the word "organic" in chemistry. [43]

  3. Composition of the human body - Wikipedia

    en.wikipedia.org/wiki/Composition_of_the_human_body

    Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium ...

  4. Nucleosynthesis - Wikipedia

    en.wikipedia.org/wiki/Nucleosynthesis

    Carbon was not made in the Big Bang, but was produced later in larger stars via the triple-alpha process. The subsequent nucleosynthesis of heavier elements (Z ≥ 6, carbon and heavier elements) requires the extreme temperatures and pressures found within stars and supernovae. These processes began as hydrogen and helium from the Big Bang ...

  5. Hydrocarbon - Wikipedia

    en.wikipedia.org/wiki/Hydrocarbon

    They are composed entirely of single bonds and are saturated with hydrogen. The formula for acyclic saturated hydrocarbons (i.e., alkanes) is C n H 2n+2. [1]: 623 The most general form of saturated hydrocarbons, (whether linear or branched species, and whether with or without one or more rings) is C n H 2n+2(1-r), where r is the

  6. History of molecular theory - Wikipedia

    en.wikipedia.org/wiki/History_of_molecular_theory

    An electron may form a part of the shell of two different atoms and cannot be said to belong to either one exclusively. Moreover, he proposed that an atom tended to form an ion by gaining or losing the number of electrons needed to complete a cube. Thus, Lewis structures show each atom in the structure of the molecule using its chemical symbol.

  7. Bicarbonate buffer system - Wikipedia

    en.wikipedia.org/wiki/Bicarbonate_buffer_system

    k H CO 2 is a constant including the solubility of carbon dioxide in blood. k H CO 2 is approximately 0.03 (mmol/L)/mmHg; p CO 2 is the partial pressure of carbon dioxide in the blood; Combining these equations results in the following equation relating the pH of blood to the concentration of bicarbonate and the partial pressure of carbon ...

  8. Timeline of hydrogen technologies - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_hydrogen...

    2016 – Toyota releases its first hydrogen fuel cell car, the Mirai. 2017 – Hydrogen Council is formed to expedite development and commercialization of hydrogen and fuel cell technologies. EMEC produces world's first tidal-powered hydrogen in Orkney, Scotland.

  9. Carbon - Wikipedia

    en.wikipedia.org/wiki/Carbon

    A similar claim can be made for hydrogen because most organic compounds contain hydrogen chemically bonded to carbon or another common element like oxygen or nitrogen. The simplest form of an organic molecule is the hydrocarbon—a large family of organic molecules that are composed of hydrogen atoms bonded to a chain of carbon atoms.