1. Names and Formulas for Ionic Compounds

2. Formula Unit Review
In ionic compounds, we must balance charges to form a neutral compound
To do that, we “crisscross the charges” similar to find the least common denominator in a fraction
Always write the cation first (metal) followed by the anion (nonmetal)
Ca and N, what will the formula be?

3. Practice
Al and S
Mg and O
Na and N

4. Formula Unit with Polyatomic ions
Sometimes you will need to use more than one polyatomic ion to balance a charge.
If so, you need to put it in parenthesis (like a package) and use a subscript for the multiple number
Ex: Mg2+ and PO43−
These charges do not balance so we must crisscross them
Mg3(PO4)2
Mg3 (PO4)2

5. Naming Ca”t”ions Monatomic cation name stays the same
Sodium, Na goes to sodium ion, Na+
Calcium, Ca goes to calcium ion, Ca 2+
Polyatomic cation - look up in chart
NH4+ ammonium
What is a cation?

6. Naming Anions The name changes in a monatomic anion
The ending for a monatomic anion is ______ide
(like a bride changes her last name)
chlorine, Cl goes to chloride ion, Cl-
Fluorine, F goes to fluoride ion, F-
Polyatomic anion look up in chart
OH- hydroxide
SO42- sulfate

7. Naming ionic compounds
Name the cation first and then the anion second (+ then -)
Example: CsF
Monatomic cations use the element name
Cs+ = cesium ion
Monatomic anions – change the ending to ide
F - = fluoride ion
cesium fluoride

8. Practice Name the following compounds NaBr sodium bromide CaCl2 KOH
calcium chloride
potassium hydroxide

9. Will these form an Ionic Compound? If so what will the formula name be?
Mg Al
Al S
Mg O
Na N
C S No
two metals
Yes
aluminum sulfide
Yes
magnesium oxide
Yes
sodium nitride No
two non-metals

10. Transition Metal Ions Transitions metals will form cations
Some transition metals only have one ionic charge
Silver (Ag+), Cadmium (Cd2+), Zinc (Zn2+)
Some transition metals can take on more than one charge.
Copper (Cu+, Cu2+)
Charge is determined from the number of electrons lost
Transition metals form compounds the same way all cations do, which enables us to find the formula units in a similar fashion.

11. Naming Transition Metal Ions
If a transition metal has more than one charge, the charge is written as a Roman numeral in parenthesis
Some metals need a middle name
Fe (iron) has more than one charge: 2+ and 3+
Fe2+ iron(II)
Fe3+ iron(III)
If the transition metal only has one charge, no Roman numeral is needed

12. Naming Ionic Compounds with Transition Metals
Given: Fe2O3
First find the charges of the ions
Then name the cation followed by the anion
Iron(III)oxide
Try this one: Fe3P2
the charge on iron is a 2+
iron(II) phosphide
Ions: O2- and Fe3+
What do we call the cation?
What do we call the anion?

13. Practice Write the formula of the compound from the name:
copper (II) nitrate
gold (I) chromate
Name the compound:
FeO
Zn(OH)2
CoPO4
iron (II) oxide
zinc hydroxide
cobalt (III) phosphate