Chemical Nomenclature and Formulas for

Ionic Compounds

Ionic Compounds

Consist of cations (positive ions) and anions (negative ions)

Usually composed of metals (cations) and nonmetals (anions)

Oxidation numbers (charges of ions) are important

Types of Ions

Monatomic ions: Consist of a single atom (Ex.: Na+, Cl-, Mg+2)

Mon = Single or one

Can often be determined from the Periodic Table

0

Predicting Ionic Charges1+ 2+ 3+ 3- 2- 1-

Types of Ions

Polyatomic ions: Groups of atoms that behave as a unit and carry a charge (Ex.: NO3

-, OH-, SO4-2)

Poly = Many or several

You will need a list of polyatomic ions to determine the name and formula

nitrate NO3 -1 chromate CrO4

-2

chlorate ClO3 -1 dichromate Cr2O7

-2

sulfate SO4 -2 phosphate PO4

-3

carbonate CO3 -2 acetate C2H3O2

-1

hydroxide OH -1 cyanide CN -1

ammonium NH4 +1

   

Binary Ionic compoundsWriting Formulas

Made up of two monatomic ions (metal and nonmetal)

Ex.: Potassium and Chlorine

Ex.: Calcium and Bromine

Binary ionic compoundsWriting Formulas

Transition Metals (Groups 3 through 12) and some metals in Groups 3A and 4A (except aluminum, cadmium, silver, and zinc) can have several oxidation numbers

Ex.: Iron (III) and Oxygen Ex.: Copper (II) and Oxygen

Ionic Compounds with Polyatomic ionsWriting Formulas

Ions made up of more than one atom

Act as individual ions

Rules used for binary compounds still apply

Use parentheses when more than one polyatomic ion is needed and use the appropriate subscripts outside of the parentheses

nitrate NO3 -1 chromate CrO4

-2

chlorate ClO3 -1 dichromate Cr2O7

-2

sulfate SO4 -2 phosphate PO4

-3

carbonate CO3 -2 acetate C2H3O2

-1

hydroxide OH -1 cyanide CN -1

ammonium NH4 +1

   

Ionic Compounds with Polyatomic ionsWriting Formulas

Example: Ammonium ion and chloride ion *IWB

Example: Calcium ion and phosphate ion *IWB

1. sodium chloride2. calcium oxide3. potassium hydroxide4. magnesium sulfide5. copper(II) carbonate6. aluminum oxide7. iron(III) oxide8. sodium carbonate9. aluminum hydroxide10. ammonium nitrate11. zinc nitrate12. magnesium carbonate

Practice Problems

Naming ionic compounds: Rules for naming ionic compounds

1. Name cation first and then the anion

CsBr Cs Br

cation anion

+ -

Naming ionic compounds: Rules for naming ionic compounds

2. Monatomic cations use the element name

Cs = cesium

3. Monatomic anions use root of the element and end with –ide

Br = bromide

CsBr = cesium bromide

+

-

Elements in Binary CompoundsElement ide NameOxygen

PhosphorousNitrogenSulfur

oxidephosphide

nitridesulfide

Naming ionic compounds: Rules for naming ionic compounds

4. This applies to transition metals and some metals in groups 3A and 4A (more than one oxidation number):

Distinguish between different oxidation numbers of the cation in the name of the chemical formula

Use a Roman numeral in parentheses after name of cation

Name Oxidation NumberCopper (I)Copper (II)

Iron (II)Iron (III)

Chromium (II)Chromium (III)

Lead (II)Lead (IV)

1+2+2+3+2+3+2+4+

Naming ionic compounds: Rules for naming ionic compounds

Examples:

Fe and O = FeO = Iron (II) oxide

Fe and O = Fe O = Iron (III) oxide

2-2+

2-3+3 2

Naming ionic compounds: Rules for naming ionic compounds

5. If compound has a polyatomic ion, simply use the name of the ion

NaOH = Na OH = sodium hydroxide

(NH ) S = NH S = ammonium sulfide

+ -

4 2 4

+ 2-

Practice Problems1. MgCl2

2. LiOH3. ZnCO3

4. K2S5. FePO4

6. Ag3N7. Mn(CN)2

8. AgC2H3O2

9. BaI2

10. PbS2