Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Chlorate polyatomic ion

  1. May 14, 2012 #1
    Hi, I was reviewing the polyatomic ions, and on the third row of the periodic table they seemed to follow a pattern going from left to right on the periodic table. For example:
    Silicate = SiO44-; phosphate = PO43-; sulfate = SO42-

    For row 3 on the periodic table, it looks like each polyatomic has 4 oxygens, the charge increases by one as one moves to the right along the periodic table, and I think the oxidation numbers of the non-oxygen elements goes +4, +5, +6, respectively. However, chlorate is ClO3-, which seems to break the pattern, since it has only 3 oxygens instead of 4, and the oxidation number on chlorine of +5, instead of +7.

    Is there any reason chlorate seems to "break" the pattern of the polyatomic ions so far, and any reason why for naming purposes, ClO3- is chlorate, instead of chlorite (like PO33- is phosphite, for example)?

  2. jcsd
  3. May 14, 2012 #2
    Well actually there is a Perchlorate ion that is ClO4 that has a negative 1 charge so the pattern isn't broken. Chlorine is just very flexible in a sense because it can have anywhere between 1-4 oxygen atoms and still have a minus 1 charge.
    ClO is Hypochlorite
    ClO2 is Chlorite
    ClO3 is Chlorate
    ClO4 is Perchlorate
    The naming has to do with the other form of the polyatomic ion can be.
  4. May 14, 2012 #3
    So is ClO4- called perchlorate simply because there is no ClO5-? I understand how perchlorate would be named relative to chlorate, and so on, but I'm trying to figure out why the naming for the other polyatomic ions I mentioned had 4 oxygens for the "ate" names. But for chlorate, the form with 3 oxygens carries the "ate" name. Thanks again for the help!
  5. May 14, 2012 #4
    In general, the most common oxyanion for an element will end in ate. You will find many trends in the periodic table, but you will also find many exceptions.

    Some examples I can think of for ate's that have 3 oxygens are nitrate, bromate, iodate, carbonate (although that has a minus 2 charge)

    And I don't think there is an element that has 5 different oxyanions.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook