dennisfrancisblewettiii
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Determining the nomenclature of oxyanions
I'm trying to understand the nomenclature of oxyanions, but I don't understand how I can look at the periodic table and tell which oxyanion has an
-ite or -ate suffix.
How do I figure it out?
Is there some kind of pattern?
I don't see much information on the web about this.
I have a hunch it has something to do with orbitals, but I'm not sure.
- Dennis Francis Blewett III
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Maya
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-ite , as in sulfites, selenites etc are -XO3 and nitrites are -NO2
whereas
-ate, as in sulfates, selenates etc are -XO4 and perchlorate ClO4 but chlorate is ClO3
Except carbonates are -CO3, Nitrates are -NO3 etc
Grab a good inorganic chem text and read thru it , you'll understand soon
[Edited on 7-2-2007 by Maya]
[Edited on 7-2-2007 by Maya]
[Edited on 7-2-2007 by Maya]
[Edited on 7-2-2007 by Maya]
\"Prefiero ser yo extranjero en otras patrias, a serlo en la mia\"
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dennisfrancisblewettiii
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That doesn't really help. Anyone have something more detailed?
- Dennis Francis Blewett III
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12AX7
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-Ate is perhaps the most common one (like sulfATE, nitrATE) that is in a relatively oxidized state. In many cases, it is the most oxidized (e.g.,
chromate, nitrate, etc.). Occasionally, higher oxidation states (more oxygen, or other electronegative elements substituting -- almost always oxygen
though) add the per- prefix, as perchlorate, ClO4-, compares to chlorate, ClO3-. Lower states are thus -ites, as sulfite, SO3(2-) (compare to sulfate
SO4(2-)), nitrite, phosphite, ferrite, etc. -Ide is the element alone in a reduced, ionic state: chloride (Cl-), sulfide (S(2-), or hydrosulfide
SH-), etc. If there is a state inbetween, it is called the hypo-[ ]-ite, as hyposulfite (better called thiosulfate), hypophosphite, etc.
You can't generalize to RO3 for -ate, as aluminate is AlO2- and phosphate is PO4(3-).
Adding to the confusion, many ions are prefixed per- to denote an O-O bond (peroxy). Thus, persulfate is effectively SO5(2-) (or the peroxydisulfate
S2O8(2-)), but in empirical formula only. Perchromate can go up to CrO6(2-), but that doesn't mean all six oxygens are crowding the chromium.
It has to do with the typical oxidation state of the central atom, or perhaps what it was identified as. (Indeed, chlorate was known before
perchlorate, but due to the richness of chlorine's oxidation states, this was fortunate, otherwise we would need something to distinguish chlorite
(ClO2-) from hypochlorite (OCl-)! On the other hand, sulfur's even more diverse combinations are dizzying.)
And if nothing else, you can always use "-ate" when specifying the oxidation state explicitly. Sodium ferrate (III) is NaFeO2 ("sodium ferrite"),
while sodium ferrate (VI) is the hard-to-make purple compound NaFeO4.
Tim
[Edited on 2-7-2007 by 12AX7]
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dennisfrancisblewettiii
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| Quote: | | It has to do with the typical oxidation state of the central atom, or perhaps what it was identified as. |
So, if I want to understand how oxyanions are determined, then I need to focus on those two things?
- Dennis Francis Blewett III
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Maya
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you need to know how many oxidation states each atom on the periodic table is capable of. some have many oxidation states , others few. just plain
memorization
\"Prefiero ser yo extranjero en otras patrias, a serlo en la mia\"
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unionised
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So far as I can tell you can either memorise them all or you can use the official IUPAC type names and call sulphates "tetraoxysulphate (VI)" and
sulphite "trioxysulphite (IV)" etc. The latter approach will get you through exams because the IUPAC names are correct; the problem is that it will
mark you out as a bit of a newbie.
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dennisfrancisblewettiii
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| Quote: | | Originally posted by unionisedthe problem is that it will mark you out as a bit of a newbie. |
I'm interested in what you mean by that. I figure you're using some type of social comparison, but I don't see the ground for comparison.
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unionised
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Re "I'm interested in what you mean by that. I figure you're using some type of social comparison, but I don't see the ground for comparison. "
Well Genecks, if you look on this site, for example, all the experienced chemists use "trivial" names for perchlorate, nitrite and the like.
A google search for "sulphate aerosols" gets tens of thousands of hits, "sulphate(VI) aerosols" gets none. (spelling sulphate with an f doesn't make
much difference).
In my experience the only people who regularly use the IUPAC names for compounds like these are the people who don't have the familiarity with the
other names.
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