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Oxidation States

  1. Jan 31, 2005 #1
    When writing oxidation states, is there a difference between 2+ and +2?
     
  2. jcsd
  3. Jan 31, 2005 #2

    Gokul43201

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    I believe convention requires that you use +n or -n to represent oxidation states, and m+ or m- to denote the net chrge on some species.

    Example : In the radical [itex]SO_4^{~2-} [/itex], the oxidation state of S is [itex]+6[/itex].
     
  4. Jan 31, 2005 #3

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    You often see the oxidation state written in Roman numerals, so SVI in Gokul's example.
     
  5. Jan 31, 2005 #4

    dextercioby

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    Even with Roman numerals,u still need the sign.Dor example Sulphur:[tex] S^{II} [/tex] is it for a metalic compound or for a nonmetalic compound...???

    Daniel.
     
  6. Feb 1, 2005 #5

    movies

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    True! I should have written S+VI.

    Often times I think that the '+' is assumed unless you use a '-'
     
  7. Feb 1, 2005 #6

    dextercioby

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    The distinction needs to be done each time an nonmetalic compound experinces more than one ON,and of opposite signs.
    So u may use the Roman Numerals at free will,just along you assure yourself that your notation will not raise confusions among the readers...

    Daniel.
     
  8. Feb 1, 2005 #7

    Gokul43201

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    I have never come across the notation, [itex]Fe^{+II} [/itex] , for example. I've usually seen Roman Numerals designate oxidation states in complexes, but then the oxidation state appears in brackets, not as a superscript.

    Ex : dichlorotetramminecobalt(III) chloride
     
  9. Feb 1, 2005 #8
    I must say that I have never come across Roman Numerials in formulae either. Is there an reason to use one instead of the other or are they interchangeable???

    The Bob (2004 ©)
     
  10. Feb 1, 2005 #9

    chem_tr

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    I remember that the notation 2+ is preferred over +2, since it can be mixed up with exponential expressions, I mean, when we write [SO4-2]-2, it may confuse somebody, which one is the electronic charge and which one is a mathematical expression? So to distinguish them, charges are written in the form n+ or n-. In my TA years, I explained the issue to the pupils like that and tried to get them used to writing like this. I hope I was not wrong.
     
  11. Feb 1, 2005 #10

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    I like chem_tr's explanation. It seems to make the most sense to me.

    Maybe the Roman numerals thing I mentioned before is outdated, or at least isn't as common as I thought it was. I'm not even sure where I learned it, but it seems like I see it fairly regularly. It's definitely something that is more associated with metals than organic molecules, probably because metals have more interesting oxidation states. I guess I always assumed that it was to denote the oxidation state of the metal without confusing it for a formal charge (as in a net neutral organometallic complex like ferrocene, which contains Fe2+).
     
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