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  2. Molecule - Wikipedia

    en.wikipedia.org/wiki/Molecule

    The smallest molecule is the diatomic hydrogen (H 2), with a bond length of 0.74 Å. [24] Effective molecular radius is the size a molecule displays in solution. [25] [26] The table of permselectivity for different substances contains examples.

  3. Chemical compound - Wikipedia

    en.wikipedia.org/wiki/Chemical_compound

    A molecule consisting of atoms of only one element is therefore not a compound. A compound can be transformed into a different substance by a chemical reaction, which may involve interactions with other substances. In this process, bonds between atoms may be broken or new bonds formed or both.

  4. Chemical bond - Wikipedia

    en.wikipedia.org/wiki/Chemical_bond

    In (a) the two nuclei are surrounded by a cloud of two electrons in the bonding orbital that holds the molecule together. (b) shows hydrogen's antibonding orbital, which is higher in energy and is normally not occupied by any electrons. A chemical bond is the association of atoms or ions to form molecules, crystals, and other

  5. Hydrate - Wikipedia

    en.wikipedia.org/wiki/Hydrate

    For example: ethanol, CH 3 −CH 2 −OH, is the product of the hydration reaction of ethene, CH 2 =CH 2, formed by the addition of H to one C and OH to the other C, and so can be considered as the hydrate of ethene. A molecule of water may be eliminated, for example, by the action of sulfuric acid.

  6. Matter - Wikipedia

    en.wikipedia.org/wiki/Matter

    A chemical substance is a unique form of matter with constant chemical composition and characteristic properties. [12] [13] Chemical substances may take the form of a single element or chemical compounds. If two or more chemical substances can be combined without reacting, they may form a chemical mixture. [14]

  7. Glossary of chemistry terms - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_chemistry_terms

    A molecule that contains double or triple bonds separated by one single bond; e.g. the compound buta-1,3-diene, with the chemical structure H 2 C=CH−CH=CH 2, has conjugated double bonds. In such molecules, there is some delocalization of electrons in the pi orbitals between the carbon atoms linked by the single bond. [3]

  8. Chemistry - Wikipedia

    en.wikipedia.org/wiki/Chemistry

    A ball-and-stick representation of the caffeine molecule (C 8 H 10 N 4 O 2) A molecule is the smallest indivisible portion of a pure chemical substance that has its unique set of chemical properties, that is, its potential to undergo a certain set of chemical reactions with other substances. However, this definition only works well for ...

  9. Chemical reaction - Wikipedia

    en.wikipedia.org/wiki/Chemical_reaction

    Cyclic rearrangements include cycloadditions and, more generally, pericyclic reactions, wherein two or more double bond-containing molecules form a cyclic molecule. An important example of cycloaddition reaction is the Diels–Alder reaction (the so-called [4+2] cycloaddition) between a conjugated diene and a substituted alkene to form a ...