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  2. Chemical substance - Wikipedia

    en.wikipedia.org/wiki/Chemical_substance

    A chemical substance is a unique form of matter with constant chemical composition and characteristic properties. [1][2] 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. [3]

  3. Chemical compound - Wikipedia

    en.wikipedia.org/wiki/Chemical_compound

    A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. 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 ...

  4. Organic compound - Wikipedia

    en.wikipedia.org/wiki/Organic_compound

    A slightly broader definition of the organic compound includes all compounds bearing C-H or C-C bonds. This would still exclude urea. Moreover, this definition still leads to somewhat arbitrary divisions in sets of carbon-halogen compounds. For example, CF4 and CCl4 would be considered by this rule to be "inorganic", whereas CHF3, CHCl3, and ...

  5. Molecule - Wikipedia

    en.wikipedia.org/wiki/Molecule

    A compound's empirical formula is a very simple type of chemical formula. [27] It is the simplest integer ratio of the chemical elements that constitute it. [ 28 ] For example, water is always composed of a 2:1 ratio of hydrogen to oxygen atoms, and ethanol (ethyl alcohol) is always composed of carbon, hydrogen, and oxygen in a 2:6:1 ratio.

  6. Carbon compounds - Wikipedia

    en.wikipedia.org/wiki/Carbon_compounds

    The number of organic compounds is immense and the known number of defined compounds is close to 10 million. [4] However, an indefinitely large number of such compounds is theoretically possible. By definition, an organic compound must contain at least one atom of carbon, but this criterion is not generally regarded as sufficient.

  7. Glossary of chemistry terms - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_chemistry_terms

    The ligand is usually an organic compound called a chelant or chelating agent. chemical See chemical species and chemical compound. chemical bond See bond. chemical composition The identity and relative number of the elements that make up a chemical compound, which can often be expressed with a chemical formula. chemical compound See compound.

  8. Mixture - Wikipedia

    en.wikipedia.org/wiki/Mixture

    A mixture is a material made up of two or more different chemical substances which can be separated by physical method.It is an impure substance made up of 2 or more elements or compounds mechanically mixed together in any proportion. [ 1 ] A mixture is the physical combination of two or more substances in which the identities are retained and ...

  9. Cellulose - Wikipedia

    en.wikipedia.org/wiki/Cellulose

    Cellulose is derived from D -glucose units, which condense through β (1→4)- glycosidic bonds. This linkage motif contrasts with that for α (1→4)-glycosidic bonds present in starch and glycogen. Cellulose is a straight chain polymer.