1. One more to throw in the mix
Polyatomic Ions
One more to throw in the mix

2. What are Polyatomic Ions?
They are charged molecules
AKA
Ions made up of more than one type of atom
Regular ion: [Na]+
Example
Polyatomic ion: [NH4]+
They have an electric charge
They cannot exist on their own

3. Memorization?
No! That’d be silly. But look at them often enough to become familiar with them
Look on pg. 192 in your text to see a list of common PA ions
Example:
Ammonium (NH4)+
When reacted with Cl- it become ammonium chloride, a flavouring agent in liquorish

4. Formula from the Name - Polyatomic
Example: manganese (III) chlorate
Figure out what these two ions are and what their charges are
manganese (III) is Mn3+
chlorate is ClO3-
Figure out how many you need of each so that the positive charge and negative charge balance out to zero
Mn has a + 3 charge so 1 Mn = +3
ClO3 has a -1 charge and 3 ClO3 = -3
List the two ions in the order they are named. Put brackets around any ions where there are more than one of them
Mn(ClO3)
Indicate how many ions are present in a subscript, right after the brackets
Mn(ClO3)3

5. Example: Ammonium Sulfate
Figure out what the two ions are and what their charges are
NH SO42-
Figure out how many of each ion you need to balance the positive and negative ions out to zero
NH4+ : = +2 (2 NH4 ions) SO42- : -2 = -2 (1 SO4 ion)
List the two ions in the order that they are named. Put brackets around any ions where there are more than one of them involved
(NH4)(SO4)
Indicate how many of each ion are present in the compound as a subscript right beside the ion (just outside of the brackets)
(NH4)2SO4
BAM !!!

6. Writing the name for a compound with a PA ion in it
Figure out what the two ions are – write out their names and charges
If they are both PA ions, then list them in the order they appear in the formula (positive ion first, negative ion second)
If the positive ion is a multivalent ion, then figure out what charge is being used and indicate it with roman numerals
If the negative ion is a simple non-metal, be sure to change the suffix to “ide”