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  2. Composition of the human body - Wikipedia

    en.wikipedia.org/wiki/Composition_of_the_human_body

    The main elements that comprise the human body (including water) can be summarized as CHNOPS. Element Symbol percent mass percent atoms Oxygen O 65.0 24.0 Carbon C 18.5 12.0 Hydrogen H 9.5 62.0 Nitrogen N 2.6 1.1 Calcium Ca 1.3 0.22 Phosphorus P 0.6 0.22 Sulfur S 0.3 0.038 Potassium K 0.2 0.03 Sodium Na 0.2 0.037 Chlorine Cl 0.2 0.024 Magnesium Mg

  3. Chemical compound - Wikipedia

    en.wikipedia.org/wiki/Chemical_compound

    [16] [17] [18] A molecule may be homonuclear, that is, it consists of atoms of one chemical element, as with two atoms in the oxygen molecule (O 2); or it may be heteronuclear, a chemical compound composed of more than one element, as with water (two hydrogen atoms and one oxygen atom; H 2 O). A molecule is the smallest unit of a substance that ...

  4. Molecule - Wikipedia

    en.wikipedia.org/wiki/Molecule

    A molecule may be homonuclear, that is, it consists of atoms of one chemical element, e.g. two atoms in the oxygen molecule (O 2); or it may be heteronuclear, a chemical compound composed of more than one element, e.g. water (two hydrogen atoms and one oxygen atom; H 2 O).

  5. Biomolecule - Wikipedia

    en.wikipedia.org/wiki/Biomolecule

    A biomolecule or biological molecule is loosely defined as a molecule produced by a living organism and essential to one or more typically biological processes. [1] Biomolecules include large macromolecules such as proteins , carbohydrates , lipids , and nucleic acids , as well as small molecules such as vitamins and hormones.

  6. Water - Wikipedia

    en.wikipedia.org/wiki/Water

    In inorganic reactions, water is a common solvent, dissolving many ionic compounds, as well as other polar compounds such as ammonia and compounds closely related to water. In organic reactions, it is not usually used as a reaction solvent, because it does not dissolve the reactants well and is amphoteric (acidic and basic) and nucleophilic .

  7. Chemical substance - Wikipedia

    en.wikipedia.org/wiki/Chemical_substance

    All compounds are substances, but not all substances are compounds. A chemical compound can be either atoms bonded together in molecules or crystals in which atoms, molecules or ions form a crystalline lattice. Compounds based primarily on carbon and hydrogen atoms are called organic compounds, and all others are called inorganic compounds.

  8. Catabolism - Wikipedia

    en.wikipedia.org/wiki/Catabolism

    This molecule acts as a way for the cell to transfer the energy released by catabolism to the energy-requiring reactions that make up anabolism. Catabolism is a destructive metabolism and anabolism is a constructive metabolism. Catabolism, therefore, provides the chemical energy necessary for the maintenance and growth of cells.

  9. Chemical composition - Wikipedia

    en.wikipedia.org/wiki/Chemical_composition

    Chemical formulas can be used to describe the relative amounts of elements present in a compound. For example, the chemical formula for water is H 2 O: this means that each molecule of water is constituted by 2 atoms of hydrogen (H) and 1 atom of oxygen (O). The chemical composition of water may be interpreted as a 2:1 ratio of hydrogen atoms ...