WRITING NAMES &
FORMULAS FOR
POLYATOMIC IONS &
RELATED OXYACIDS
Textbook Pages: 66 – 67, 69 - 70
Polyatomic Ions
• Definition: A polyatomic ion is a group of atom that stay
together and have an overall ionic charge.
• Example: NO3−
Nitrate ion
• ***Refer to the back of your Periodic Table for a list of
the Polyatomic Ions!!!
The “Standard” Polyatomic Ions
• There is a special way to name these ion. The following
are the most common forms of the ions:
• The Standards:
• ClO3 • BrO3 –
• IO3 • NO3 • SO4 2−
• CO3 2−
• PO4 3−
Polyatomic Ions:
chlorate ion
bromate ion
iodate ion
nitrate ion
sulphate ion
carbonate ion
phosphate ion
***All “standard”
polyatomic ions
end in “ate”
Altering the Number of Oxygens in
Polyatomics
• 1. If there is one more Oxygen than the standard ion, the
ion follows the following pattern:
per ________ ate
• Example:
ClO4−
perchlorate
• Note: the charge does not change, it stays the same as
the standard/original polyatomic ion.
Altering the Number of Oxygens in
Polyatomics
• If there is one less Oxygen then the standard ion, the ion
follows the following pattern:
________ ite
• Example:
ClO2−
chlorite
• Note: the charge does not change, it stays the same as
the standard/original polyatomic ion.
Altering the Number of Oxygens in
Polyatomics
• 3. If there are two less Oxygen than the standard ion,
then the ion follows the following pattern:
hypo ________ ite
• Example:
ClO−
hypochlorite
• Note: the charge does not change, it stays the same as
the standard/original polyatomic ion.
Oxyacids
• Definition: Oxyacid is an acid composed of hydrogen,
oxygen, and atoms of at least one other element.
• Oxyacids follow the pattern:
ic acid
• Example:
HClO3
Chloric Acid
Oxyacids
• There is a special way to name these acids.
• The Standards:
• HClO3
• HBrO3
• HIO3
• HNO3
• H2SO4
• H2CO3
• H3PO4
Oxyacids (Add H+):
chloric acid
bromic acid
iodic acid
nitric acid
sulphuric acid
carbonic acid
phosphoric acid
***All “standard”
oxyacids take the
format :
______ ic acid
Altering the Number of Oxygens in
Oxyacids
• 1. If there is one more Oxygen that the standard, the acid
follows the following pattern:
per ________ ic acid
• Example:
HClO4
perchloric acid
Altering the Number of Oxygens in
Oxyacids
• 2. If there is one less Oxygen that the standard, the acid
follows the following pattern:
________ ous acid
• Example:
HClO2
chlorous acid
Altering the Number of Oxygens in
Oxyacids
• If there are two less Oxygen than the standard, the acid
follows the following pattern:
hypo ________ ous acid
• Example:
HClO
hypochlorous acid
*** Remember:
PRACTICE MAKES
PERFECT!!!!
SO PRACTICE A
LOT!!!!!!!!!!