1. Naming Ionic Compounds

2. Monatomic Ions
 Made from a single atom gaining or
losing an electron (based on valence
electrons)
Element Oxidation #
Li +1
Be +2
O -2
F -1
 Writing ions- write symbol, write charge
as a superscript
Ex. Al+3

3. Writing Ionic Compounds
 Made of two parts – cation & anion
 Name the cation first (typically a
metal) just as it appears on periodic
table
Na+  Sodium
Ca+2  Calcium

4. Writing Ionic Compounds with
Transition Metals
 Most transition metals have more than
one oxidation number
 If the transition metal has more than
one oxidation number, you must
represent it with a Roman Numeral in
its name

5. Transition Metals to know
 Scandium column – always +3, no
Roman Numeral needed
 F-block – always +3, no Roman
Numeral needed
 Ag – always +1, no Roman Numeral
needed
 Cd & Zn – always +2, no Roman
Numeral needed

6. Transition Metals to know (cont.)
 Sn & Pb – either +2 or +4
 Sn & Pb and all other transition
metal’s oxidation # will be determined
by “uncrossing the criss-cross”
(I’ll explain in a minute)
Examples:
Fe+2  Iron II Fe+3  Iron III
Al+3  Aluminum Cu+2  Copper II
Cu+  Copper I Zn+2  Zinc

7. Writing Ionic Compounds (cont.)
 Write the anion next (typically a
nonmetal)
 Change the ending to –ide
Cl- , chlorine  chloride
O-2 , oxygen  oxide
**If the anion is a polyatomic ion, the
name stays the same**

8. Writing Ionic Compounds
Practice
NaCl Sodium Chloride
FeS Iron II Sulfide
AlCl3 Aluminum Chloride
Na2O Sodium Oxide
Al2O3 Aluminum Oxide
CuO Copper II Oxide

9. How to determine the Oxidation
Number of Transition Metals
 Identify metal as a Transition with
multiple oxidation numbers
 Uncross the “criss-cross”
 If nothing to uncross, identify the
charge of the anion (they will always
only have one oxidation
number), charges have been
simplified
 Transition metal charge is the same
as anion charge (just +)

10. How to determine the Oxidation
Number of Transition Metals
(cont.)
Ex. #1
Fe2O3
+3 -2
Fe2O3
Iron III Oxide

11. How to determine the Oxidation
Number of Transition Metals
(cont.)
Ex.#2
FeS
**No subscripts to show charge, so ID
anion charge
 S = -2, therefore Fe must be +2
 Name = Iron II Sulfide
Ex.#3
CuO
 Name = Copper II Oxide

12. Writing an Ionic Formula
 Identify the charge on each part of the
compound (cation and anion)
 Remember…the sum of the oxidation
numbers MUST EQUAL ZERO
 Add subscripts to balance charges
(can be done with criss-cross method)

13. Writing an Ionic Formula
(cont.)
Ex. #1 = Calcium Chloride
Ions  Ca = +2 Chlorine = -1
+2 -1
Ca Cl
Formula = CaCl2
(Remember…never write 1’s)

14. Writing an Ionic Formula
(cont.)
Ex.#2 = Magnesium Oxide
Ions  Mg = +2 O = -2
Use “criss-cross”  Mg2O2
**Simplify when possible  MgO

15. Extra Rule
Can’t change a Polyatomic Ions
subscripts (if you need multiple
polyatomics, you must put the ion
symbol in brackets)
Ex. PO4 = has a -3 charge
Ca = has a +2 charge
Formula = Ca3(PO4)2

16. Changes to Polyatomic Ions
 We must know the “root” polyatomic
ion (the ones on our list)
 Oxygens can either be added or
subtracted from the formula we know
 When that happens, the polyatomic
ion name changes

17. Changes to Polyatomic Ions
(cont.)
1 more oxygen  per-
-ate
Root 
-ate
1less oxygen  -ite
2 less oxygens  hypo-
-ite
**the charge remains the same**
Ex. SO5 = Persulfate SO4 =
Sulfate