NAME:___________________________________
DATE:_____________________
PERIOD:_____
#:_____
Writing Ionic Formulas Notes
Ionic Compounds Review
Ionic compounds are always made up of a _______________ and a _______________.
Two types of ionic compounds:
1. Binary: _______________________________________________________________
2. Polyatomic: ___________________________________________________________
Criss-Cross Method – Calcium & Nitrogen Example
1.
2.
3.
4.
Additional Examples:
Aluminum & Oxygen
Sodium & Sulfur
Aluminum & Nitrogen
Writing Ionic Formulas Notes
Practice Problems
Beryllium & Bromine
Lithium & Oxygen
Potassium & Nitrogen
Calcium & Sulfur
Magnesium & Nitrogen
Aluminum & Phosphorus
Lithium & Chlorine
Magnesium & Oxygen
Calcium & Iodine
Ionic Formulas with Transition Metals
Transition metals (___________________) can form more than one type of cation. Also,
_________ and ________ can form more than one type of cation.
The charge for transition metals is always ____________________ and can be found in
the name of the compound that contains them (the _____________________________
indicates the charge).
Examples:

iron (II) is
_______

lead (IV) is
_______
Writing Ionic Formulas Notes
Practice Problems
Iron (III) & Oxygen
Tin (II) & Sulfur
Lead (II) & Chlorine
Iron (II) & Nitrogen
Lead (IV) & Oxygen
Ag (I) & Phosphorus
Ionic Compounds with Polyatomic Ions
Polyatomic ions are ___________________ of atoms that stay together as _________________
and carry an overall charge.
Parentheses: You may need more than one polyatomic ion in your formula. This means that
you will have to use parentheses.
***Use parentheses whenever you need more than one polyatomic ion in the formula***
Example: Iron (III) nitrate…
SYMBOLS: ______ and ______

After you criss-cross, you may get one of two possibilities…
FeNO33 OR Fe(NO3)3
The second option is right because it says you need two nitrate clusters to go
with every iron atom. The first option, which did not use parentheses, reads as
one iron atom with one nitrogen atom and thirty-three oxygen atoms.

Fe(NO3)3 is the correct formula! Use parentheses!
Writing Ionic Formulas Notes
Practice Problems
Name
Cation
Anion
Sodium nitrate
NO3-
Calcium chlorate
ClO3-
Lithium phosphate
PO43-
Aluminum sulfate
SO42-
Tin (IV) carbonate
CO32-
Iron (II) hydroxide
OH-
Magnesium carbonate
CO32-
Lead (II) bicarbonate
HCO3-
Potassium chlorate
ClO3-
Ammonium phosphate
NH4+
PO43-
Formula of Compound