Chapter 8Chemistry 1L

Cypress Creek High School

Unit 8: Ionic Unit 8: Ionic BondsBonds

Part 2: Naming Part 2: Naming and Writing and Writing

Formulas for Ionic Formulas for Ionic CompoundsCompounds

Ionic Bonds – Writing FormulasIonic Bonds – Writing Formulas

• Sodium and chlorine bond in a 1:1 ratio to form NaCl

• Calcium and chlorine bond in a 1:2 ratio for form CaCl2

• What determines each ratio & formula? ________________oxidation numbers

Ionic Bonds – Writing FormulasIonic Bonds – Writing Formulas• CRISS-CROSS METHOD– Oxidation numbers (excluding charge) of each ion trade

places to become the subscripts in the formula – must be reduced to lowest whole number ratio; 1’s are not written

Ca & S

Ca2S2

Al & Cl

AlCl3

3+ 1- 2+ 2-

CaS

Ionic Bonds – Writing FormulasIonic Bonds – Writing Formulas

Ions Oxidation Numbers Ratio Formula

Magnesium & Oxygen Mg2+ & O2- 1:1 MgO

Lithium &Sulfur

Aluminum & Oxygen

Sodium & Phosphorus

Barium &Fluorine

• Try to predict the ratio and resulting formula for each of the following ions based on their oxidation numbers:

Li+ & S2- 2:1 Li2S

Al3+ & O2- 2:3 Al2O3

Na+ & P3- 3:1 Na3P

Ba2+ & F- 1:2 BaF2

Three Types of Ionic CompoundsThree Types of Ionic Compounds

• We will learn how to write nomenclature for:– Binary Salts• 2 elements: a metal and a nonmetal

– Ternary Salts• 3 or more elements• Includes a polyatomic ion

– Salts with Multiple Oxidation Numbers• Can be binary or ternary• Includes a transition metal

Binary Salt NamingBinary Salt Naming• Contains 2 elements: cation & anion• Naming:

– Name the cation (no changes)– Drop the end of anion and add “ide”

• Example: MgCl2 = magnesium chloride

Binary Salt NamingBinary Salt Naming

Ions Oxidation Numbers Ratio Formula Name

Magnesium & Oxygen Mg2+ & O2- 1:1 MgO magnesium

oxide

Lithium &Sulfur

Li+ & S2- 2:1 Li2S

Aluminum & Oxygen Al3+ & O2- 2:3 Al2O3

Sodium & Phosphorus Na+ & P3- 3:1 Na3P

Barium &Fluorine

Ba2+ & F- 1:2 BaF2

• We’ve already predicted these formulas. Now, try to predict the names for each binary salt:

lithium sulfide

aluminum oxide

sodium phosphide

barium fluoride

Polyatomic IonsPolyatomic IonsName Formula

acetate C2H3O2- or CH3COO-

ammonium NH4+

carbonate CO32-

chlorate ClO3-

chlorite ClO2-

chromate CrO42-

cyanide CN-

dichromate Cr2O72-

hydrogen carbonate HCO3-

hydroxide OH-

hypochlorite ClO-

nitrate NO3-

nitrite NO2-

perchlorate ClO4-

permanganate MnO4-

phosphate PO43-

sulfate SO42-

sulfite SO32-

• Some ions contain more than one element - called a polyatomic ion

• The group as a whole has an overall charge

• Examples:– Lithium and sulfate would

bond together to make Li2SO4

– Ammonium and sulfur would bond together to make (NH4)2S

Ternary Salt NamingTernary Salt Naming

• Contains 3 or more elements: cation & anion – most polyatomic ions are anions, only cation is ammonium (NH4

+)

• Naming:– Name the cation (no changes)– Name the anion (no changes)

• Example: Na2SO4 = sodium sulfate

• Exception: When ammonium is paired with an element anion– NH4Cl = ammonium chloride

Ternary Salt FormulasTernary Salt Formulas• You must use parentheses if you have more

than one polyatomic ion. Be sure to criss-cross the oxidation numbers and write it OUTSIDE of the parentheses.

K & PO4

K3PO4

Al & SO3

Al2(SO3)3

3+ 2- + 3-

Ternary Salt Formulas & NamingTernary Salt Formulas & Naming

Ions Oxidation Numbers Ratio Formula Name

Potassium & Hydroxide K+ & OH- 1:1 KOH potassium

hydroxide

Calcium & Carbonate

Barium & Nitrate

Sodium & Phosphate

Ammonium & Sulfur

• Try to predict the formulas and names for each ternary salt:

Ca2+ & CO32- 1:1 CaCO3

calcium carbonate

Ba2+ & NO3- 2:1 Ba(NO3)2

barium nitrate

Na3PO4Na+ & PO43- 1:3 sodium

phosphate

NH4+ & S2- 1:2 (NH4)2S

ammonium sulfide

Salts with Multiple Oxidation #s NamingSalts with Multiple Oxidation #s Naming

• Transition elements can form more than one type of positive ion. – For example, copper can form both Cu+ and Cu2+ ions,

and iron can form both Fe2+ and Fe3+ ions. – Zinc and silver are two exceptions – they only have

one oxidation number • The zinc ion is Zn2+ and the silver ion is Ag+.

• Naming:– Name the cation– Put the roman numeral representing the oxidation # of the

metal in parentheses (do not indicate the charge)– Name the anion, changing the ending to “ide” (binary) or

naming the polyatomic ion (ternary)• Example:

– FeCl2 = iron (II) chloride– FeCl3 = iron (III) chloride

Salts with Multiple Oxidation Salts with Multiple Oxidation Numbers PracticeNumbers Practice

Ions Oxidation Numbers Ratio Formula Name

Copper & Nitrate

Cu+ & NO3- 1:1 CuNO3

copper (I) nitrate

Lead &Oxygen

Cobalt & Hydroxide

Nickel & Phosphate

Chromium & Sulfur

Pb4+ & O2- 2:1 PbO2lead (IV)

oxide

Co3+ & OH- 3:1 Co(OH)3cobalt (III) hydroxide

Ni2+ & PO43- 2:3 Ni3(PO4)2

nickel (II) phosphate

Cr2+ & S2- 1:1 CrS chromium (II) sulfide