Oxyanions
Some elements are able to form more than one oxyanion (polyatomic
ions that contain oxygen), each containing a different number of oxygen
atoms. For example, chlorine can combine with oxygen in four ways to form
four different oxyanions: ClO4 The most common of the chlorine oxyanions
is chlorate, ClO3 The anion with one more oxygen atom than the (root)ate
anion is named by putting per-
at the beginning of the root and
-ate at the end. For example, ClO4 The anion with one fewer oxygen atom than the (root)ate
anion is named with -ite on the end of the root. ClO2 The anion with two less oxygen atoms than the (root)ate
anion is named by putting hypo-
at the beginning of the root and
-ite at the end. ClO
Common Polyatomic ions that end in -ate NO3- nitrate SO42- sulfate PO43- phosphate ClO3- chlorate BrO3- bromate IO3- iodate
Different number of oxygen atoms
If you memorize that nitrate is NO3
Some polyatomic ions like
HCO3 Systematic and Nonsystematic Names for Some Polyatomic Ions
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EXAMPLE 1 - Naming Polyatomic Ions: Write names that correspond to the following formulas for polyatomic ions: (1) PO33- (with barium ions in glass)
(2) HSO4 Solution:
1. PO33 2. HSO4- is hydrogen sulfate. This could be called by its nonsystematic name, bisulfate, but it is preferable to use the systematic name, which shows that one H+ ion has been added to sulfate, SO42-.
EXAMPLE
2 - Formulas for Polyatomic Ions:
Write formulas that correspond to the following names for
polyatomic ions:
(1) bromite ion, used in the production of cloth (2) dihydrogen hypophosphite ion, used with manganese(II) ions as a food additive.
2. Dihydrogen hypophosphite ion is
H2PO2
Exercise 1 - Naming Polyatomic Ions:
Write names that correspond to the following formulas for
monatomic ions: IO3
Exercise 2 - Formulas for Polyatomic Ions: Write formulas that correspond to the following names for polyatomic ions: sulfite ion (preservative) and hydrogen phosphate ion (in animal feed supplements). |