SNC2D1
Date:__________________
Name:_____________________
L7: 5.9 Polyatomic Ions
Recall: Types Of Ionic Compounds
1. ____________ ionic compound (2 elements): There are 2 types: simple and multivalent metals  completed
2. ________________ ionic compound (3 or more elements)  now
Poly  means ___________
________________________
Polyatomic Ions  ions that are made up of _____________types of atoms that act as a single charged particle (the ionic charge is
shared over the entire ion). Below are some common polyatomic ions. The polyatomic can be an ___________________________
Polyatomic Ion
Ammonium
Acetate
bicarbonate
carbonate
chlorate
chlorite
chromate
cyanide
Ion Formula
NH4+
C2H3O2HCO3CO3 2ClO3ClO2CrO42CN-
Ion charge
Polyatomic Ion
hydrogen carbonate
hydroxide
nitrate
nitrite
permanganate
phosphate
sulfate
sulfite
Chemical Formula
HCO3 OHNO3 NO2 MNO4PO43SO42SO32-
Ion charge
Can you identify the polyatomic ion formula that is on the list twice?
Naming Polyatomic Ionic Compounds
1. Write the name of the cation first. If it is a multivalent metal, use the charge of the anion and the total ionic charge to
determine the charge on the metal. Remember the overall charge of the whole molecule is neutral.
2. Write the name of the anion.
3. Use the list above (or text p. 202 table 1) to help with the polyatomic ions.
Practice,
Mg(NO3)2
CaCO3
Fe(NO2)3
CuSO3
Writing the Chemical Formula for Multivalent Ionic Compounds
1. Write the symbols of the cation and the anion. Put a bracket around the polyatomic ion if it is not there already.
2. Write the ionic charge above the cation and the anion.
3. Use the cross down method. Reduce if possible (outside the bracket only).
4. Remove the brackets if the subscript outside the bracket is 1.
5. Double check that the total ionic charge is zero.
Practice 1: Write the chemical formula for
a) sodium nitrate
b) calcium hydroxide
c) magnesium phosphate
Homework: Read Section 5.9, complete p.205 # 1 – 7, 9 - 11 and worksheet
d) ammonium sulfide