# Making Ionic Compounds With Multiple Charges Worksheet

Making Ionic Formulas
Purpose: During this activity, use the models to construct neutrally charged ionic compounds.
Below is a diagram of the three cations (monovalent, divalent, trivalent) and the three anions (also
monovalent, divalent, and trivalent. A monovalent ion has a charge of plus or minus 1, divalent has
a charge of plus or minus 2 and trivalent has a charge of plus or minus charge.
CATIONS
ANIONS
-
+
-
-
+
+
+
+
-
-
+
+
-
+
Procedure:
1. Remove the models from your baggie. Arrange the pieces to fit the pattern shown above.
Each piece will represent a generic ion. For example the +1 ion could be K
1+
, or NH 4
1+
, and
1-
3 1-
the -1 ion could represent Cl
, or NO
.
2. Assume you have a generic +1 ion (X
1+ )
joined to a generic -1 negative ion (Y
1-
). Using your
models make the appropriate pieces fit together in lock-and-key manner. Make the positive ion be
on the left side and the negative ion on the right.
Follow-up Questions:
Q1. Is the resulting compound neutrally charged?
Q2. Write the formula for the compound involving (X 1+ ) and (Y 1- ). Are the charges still shown?
Why or why not? (Remember achieving neutrality is the goal.)
Q3. Write the formula for the following pairs of monovalent ions. (The positive ion is written first.)
1+
1-
1+
1-
1+
1-
A) Li
and Br
B) Cs
and F
C) H
and Cl
In question three all the monovalent ions were monatomic which means each ion has just one atom.
Some monovalent ions are polyatomic. Here are seven polyatomic ions we have to memorize:
NH
4 1+
(ammonium), OH
1-
(hydroxide), NO
(nitrate), C
H
O
2 1-
(acetate), (carbonate) CO
3 2- ,
1-
3
2
3
4 2-
4 3-
(sulfate) SO
and (phosphate) PO
. To write formulas using polyatomic ions you cannot change
the subscripts of the polyatomic ion itself. What is important is to balance the charges of positive
and negative ions.
Q4. Write the formula for the following monovalent ions (with polyatomic ions present).
A) Na
1+
and NO
3 1-
B) NH
4 1+
and Br
1-
C) K
1+
and OH
1-
D) NH
4 1+
and NO
3 1+