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Help with definitions of dioxide and oxide

  1. Jun 8, 2012 #1
    Here is the definition of oxide I found in a dictionary:
    A compound of one oxygen atom combined with another element.

    And here is the definition of dioxide that I found in a dictionary:
    An oxide containing two atoms of oxygen in each molecule; binoxide.

    Now my question/confusion is, according to the above definitions I'm thinking to myself that if an oxide is just ONE compound/molecule, that's composed of an atom of oxygen and another element, then howcome for the definition of dioxide it says, "An oxide containing two atoms of oxygen in EACH molecule"!?

    So what's the deal? Does an oxide consist of only one molecule or more?!
  2. jcsd
  3. Jun 8, 2012 #2
    Oxide has only a single oxygen atom in one molecule(of the compound), example, ZnO, CaO.

    ZnO is one single compound molecule that has one oxygen atom.

    A dioxide has two oxygen atoms in one molecule, example, CO2, SiO2 etc.

    CO2 - a dioxide, is a molecule, that has two oxygen atoms.
  4. Jun 8, 2012 #3

    Simon Bridge

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    What he said - I'd add that you should go to a technical dictionary for a technical definition.

    You are thinking that the definition given for a dioxide kinda implies that an oxide may also refer to a molecule with more than one oxygen.
    Wikipedia, for example, concurs with Foundations of College Chemistry, 12th Edition as it's source.

    You should be aware that there are inconsistencies in any language use - for instance CO is carbon monoxide and not carbon oxide to emphasize the single oxygen but ZnO is zinc oxide even though a dioxide of zinc ZnO₂ exists... (which can also be called "zinc peroxide").

    You'll notice that hydrogen peroxide is H₂O₂ which is properly "dihydrogen dioxide" ... such things occur all the time.

    What Infinitum relates is what you should understand where the context does not make it clear that another meaning is intended.

    Apart from that - sure: an oxide is a single molecule. The two definition don't contradict each other on this to my reading.
    Last edited: Jun 8, 2012
  5. Jun 8, 2012 #4


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    I don't like this definition, if anything it fits "monoxoide".

    In common usage of the word oxide is any compound of oxygen with other element, regardless of the number of atoms. So FeO is an iron oxide, Fe2O3 is an iron oxide and Fe3O4 is an iron oxide as well.

    There are ways of making names unambiguous - for example FeO is iron(II) oxide, Fe2O3 is iron(III) oxide and Fe3O4 is iron(II,III) oxide. If memory serves me well at present IUPAC naming would be diiron trioxide and triiron tetraoxide for the latter two oxides, but I am not sure if FeO is properly called monoiron monooxide.
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