Ionic Bonding and Nomenclature

Naming and Writing Formulas for Ionic Compounds

Naming and Writing Formulas for Ionic CompoundsObjectives1. Name and write the symbols for common anions,

cations, and polyatomic ions.2. Determine the formula of an ionic compound

between any two given ions.3. Name ionic compounds, given their formulas.4. Correctly use Roman numerals when naming

compounds containing transition metals with more than one oxidation number.

5. Write formulas for ionic compounds, given their names.

Back to main menu

Naming and Writing Formulas for Ionic Compounds

In forming a chemical compound, an atom can gain, lose or share one or more valence electrons.

Back to main menu

Positive Ions

A cation is an atom or group of atoms with a positive charge.

A cation has fewer electrons than a neutral atom of the element.

Back to main menu

Symbols of Ions for CationsThe metals in groups 1, 2 and 13 lose electrons when they form ions.

Group 1 forms +1 ions.Group 2 forms +2 ionsGroup 13 forms +3 ions.

Back to main menu

Naming and Writing Symbols for Cations

Back to main menu

Element Symbol of Ion Name of Ion

Calcium

Sodium

Aluminum

Ca2+ Calcium ionNa+ Sodium ion

Al3+ Aluminum ion

Metals with More than One Common Oxidation Number

The metals in groups 3-12 are called transition metals.

They often have more than one common oxidation number (ionic charge).

Back to main menu

Metals with More than One Common Oxidation NumberHere are some of the more commonly used transition metals and their oxidation numbers. Notice that a Roman numeral is used to indicate the charge on the ion when naming the ions formed.

Back to main menu

Fe2+ Iron(II) ion Fe3+ Iron(III) ionCu+ Copper(I) ion Cu2+ Copper(II) ionHg2

2+ Mercury(I) ion Hg2+ Mercury(II) ionPb2+ Lead(II) ion Pb4+ Lead(IV) ionSn2+ Tin(II) ion Sn4+ Tin(IV) ionCr2+ Chromium(II) ion Cr3+ Chromium(III) ionCr6+ Chromium(VI) ionMn2+ Manganese(II) ion Mn3+ Manganese(III) ionCo2+ Cobalt(II) ion Co3+ Cobalt(III) ionNi2+ Nickel(II) ion Ni3+ Nickel(III) ionAg+ Silver ionZn2+ Zinc ionCd2+ Cadmium ion

Negative IonsAn anion is an atom or group of atoms with a negative charge.

An anion has more electrons than a neutral atom of the element.

Group 17 forms -1 ions.Group 16 forms -2 ions.Group 15 forms -3 ions.

The names of monatomic anions end in ide.Back to main menu

Naming and Writing Formulas for Anions

Back to main menu

Element Symbol of Ion Name of Ion

Chlorine

Nitrogen

Oxygen

Cl- Chloride ionN3- Nitride ion

O2- Oxide ion

You Try ItComplete the following table.

S2-

Back to main menu

Symbol of Ion

Name of Ion Number of Electrons Lost or Gained

Sulfide ionCu+

Barium ion

Al3+

Iron(III) ionLi+

Phosphide ion

2 e- gainedCopper(I) ion 1 e- lost

Ba2+ 2 e- lostAluminum ion 3 e- lost

Fe3+ 3 e- lostLithium ion 1 e- lost

P3- 3 e- gained

Predicting Formulas of Ionic Compounds

Ionic compounds are composed of charged particles called ions.

They are electrically neutral. This means that the total positive charge is equal to the total negative charge.

Binary ionic compounds usually consist of a metal, such as an alkali metal, bonded to a nonmetal, such as a halogen.

Empirical formulas are used to represent ionic compounds. An empirical formula is the simplest ratio in which the atoms combine to form a compound.Back to m

ain menu

Predicting Formulas of Ionic Compounds

Examples: Write the formulas for the compounds formed between the following pairs of ions.

Back to main menu

a. K+, Cl-

b. Mg2+, S2-

c. Na+, S2-

d. Al3+, S2-

e. Sn4+, O2-

KClMgSNa2SAl2S3

SnO2

You Try ItWrite the formulas for the following binary ionic compounds. Hint: First determine the symbols for the ions involved. Always write the cation first. The first one has been done for you as an example.

Back to main menu

a. Sodium bromide

b. Magnesium sulfide c. Copper(I) chlorided. Calcium bromidee. Strontium fluoride

Na+, Br-

Mg2+, S2-

Cu+, Cl-

Ca2+, Br-

Sr2+, F-

NaBrMgSCuClCaBr2

SrF2

You Try ItWrite the formulas for the following binary ionic compounds. Hint: First determine the symbols for the ions involved. Always write the cation first. The first one has been done for you as an example.

Back to main menu

f. Sodium oxide g. Lead(II) bromide h. Zinc sulfidei. Aluminum oxidej. Chromium(VI) nitride

Na+, O2-

Pb2+, Br-

Zn2+, S2-

Al3+, O2-

Cr6+, N3-

Na2O

PbBr2

ZnSAl2O3

CrN2

Naming Binary Ionic Compounds

Binary ionic compounds are named by writing the name of the cation followed by the name of the anion (-ide ending).

Back to main menu

a. Na2S

b. LiFc. BaCl2

Sodium sulfideLithium fluorideBarium chloride

Roman NumeralsSometimes it is necessary to use a Roman numeral when naming an ionic compound.

Back to main menu

When do you use a Roman numeral when naming an ionic compound?

You use a Roman numeral when the metallic element forms more than one common ion. This is common of the transition metals.

CuCl isCuCl2 is

Copper(I) ChlorideCopper(II) Chloride

Roman NumeralsNever use a Roman numeral when the metallic element is from Group 1, Group 2, or for aluminum, cadmium, zinc or silver.

Back to main menu

Circle the compounds below that would need a Roman numeral when naming them.

SnCl2 Fe2O3 BaCl2 LiF

MgS CaO SrF2 CoI3

Roman NumeralsHow do I determine the charge of the Roman numeral?

Back to main menu

To determine the charge of the Roman numeral you have to first identify the ions making up the compound.

Roman NumeralsExamples.

Back to main menu

Fe2O3

Iron(III) oxide Ions Chemical

Formula Name of Compound

Fe3+, O2-

Cu+, S2-

CoI2

Tin(IV) oxideFeSCu3N

Cu2S Copper(I) sulfideCo2+, I- Cobalt(II) iodide

Sn4+, O2- SnO2

Fe2+, S2- Iron(II) sulfideCu+, N3- Copper(I) nitride

You Try ItWrite formulas for the following compounds. Remember to determine the ions involved first.

Back to main menu

Name of Compound Ions Formula of

CompoundLithium oxideTin(IV) sulfideBarium nitride

Sodium fluoride

Li2OLi+, O2-

Sn4+, S2- SnS2

Na+, F-

Ba2+, N3- Ba3N2

NaF

You Try ItName the following compounds.

Back to main menu

a. CaSb. FeNc. K2O

d. PbO

Calcium sulfideIron(III) nitridePotassium oxideLead(II) oxide

Naming and Writing Formulas for Ternary Ionic CompoundsTernary ionic compounds contain more than two elements. They usually contain one or more polyatomic ions.

Back to main menu

Common Polyatomic Ions1- Charge 2- Charge 3- Charge

Perchlorate ClO4- Carbonate CO3

2- Phosphate PO43-

Chlorate ClO3- Sulfate SO4

2- Phosphite PO33-

Chlorite ClO2- Sulfite SO3

2-

Hypochlorite ClO- Chromate CrO42 1+ Charge

Nitrate NO3- Dichromate Cr2O7

2- Ammonium NH4+

Nitrite NO2- Oxalate C2O4

2-

Iodate IO3- Silicate SiO3

2-

Bromate BrO3- Hydrogen Phosphate HPO4

2-

Permanganate MnO4-

Hydroxide OH-

Cyanide CN-

Acetate C2H3O2-

Dihydrogen phosphate H2PO4-

Hydrogen Sulfite (bisulfate) HSO3-

Hydrogen sulfate (bisulfate) HSO4-

Hydrogen carbonate (bicarbonate) HCO3-

Writing Formulas for Ternary Ionic Compounds

Writing the formulas for ternary ionic compounds is just like writing the formula for binary ionic compounds. You write the symbol and charge of the ions involved and then balance the charges.

Back to main menu

Writing Formulas for Ternary Ionic CompoundsExamples:

Back to main menu

a. K+, NO3-

b. Ba2+, PO43-

KNO3

Ba3(PO4)2

You Try It1. Write the formulas for the following

ternary ionic compounds, given the ions involved.

Back to main menu

a. Ca2+, SO42-

b. K+, PO43-

c. NH4+, N3-

d. Al3+, SO42-

CaSO4

K3PO4

(NH4)3N

Al2(SO4)3

You Try It2. Write the formulas for the following

ternary ionic compounds given their names.

Back to main menu

Lithium hypochlorite

Sodium sulfiteCalcium acetateBarium phosphateCopper(II) nitrite

LiClONa2SO3

Ca(C2H3O2)2

Ba3(PO4)2

Cu(NO2)2

Li+, ClO-

Na+, SO32-

Ca2+, C2H3O2-

Ba2+, PO43-

Cu2+, NO2-

You Try It3. To name a compound, write the

name of the cation followed by the name of the anion.

Back to main menu

a. Ca(NO3)2

b. K2SO4

c. PbSO3

d. NaC2H3O2

e. (NH4)2S

Calcium nitratePotassium sulfateLead(II) sulfiteSodium AcetateAmmonium sulfide