Hydroxide Ion

  1. Why does the hydroxide ion have a negative charge? , i.e OH-?
     
  2. jcsd
  3. DrDu

    DrDu 4,092
    Science Advisor

    Because if not, it would be a hydroxide radical and not an ion?
     
  4. Think octet rule and lewis dot structures... you need one more electron to make the oxygen stable, so it has a 1- charge.
     
  5. adjacent

    adjacent 1,533
    Gold Member

    The simplest way for explaining this is this:
    O2-+H+=(OH)- (It's actually (OH)-)

    This is not stable(Stable form is H2O)

    Here H+ Cancels out one electron of O2-

    So one electron is left.Therefore it is left with a negative charge
    -2+1=-1
    :wink:
     
  6. Count the number of protons and number of electron in the ion.
    With reference to what Drdu said: ions are charged, radicals are neutral.
    :smile:chemistry sometimes overcomplicates things to simplify them...
     
  7. Radicals need not always be neutral.

    See: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2644638/

    Also you can have stuff like the superoxide anion which is a anion radical. See: http://en.wikipedia.org/wiki/Superoxide

    Plenty of examples around, these are just off the top of my head.
     
  8. Sorry for not being clearer, I was talking about hydroxyl radicals which DrDu mentioned rather than radicals in general.
    As for the definition of radical I believe the only prerequisite is having an unpaired electron/ incompletely filled valence shell and the species in question may be an atom, ion or a molecule.
     
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