Naming and Writing Naming and Writing FormulasFormulas

Types of CompoundsTypes of Compounds

There are two types of compounds.There are two types of compounds.

Ionic: Ionic: a metal and an nonmetala metal and an nonmetal

Covalent: Covalent:

contain two nonmetalscontain two nonmetals

Ionic CompoundsIonic Compounds Must contain a positive ion (cation) Must contain a positive ion (cation)

and negative ion (anion).and negative ion (anion).

The cation (metal) is written first, the The cation (metal) is written first, the anion (nonmetal) is written second.anion (nonmetal) is written second.

The total charge on the compound The total charge on the compound must equal 0.must equal 0.

Naming Binary Ionic Naming Binary Ionic CompoundsCompounds

#1 – Name the metal (written on periodic #1 – Name the metal (written on periodic table)table)

#2 – Name the nonmetal, #2 – Name the nonmetal, changing the ending to –idechanging the ending to –ide..

Examples:Examples: MgOMgO CaClCaCl22 NaBrNaBr SrSr33PP22

magnesium oxidemagnesium oxide calcium chloridecalcium chloride sodium bromidesodium bromide strontium strontium

phosphide phosphide

Writing FormulasWriting Formulas

The subscripts tell how many of each The subscripts tell how many of each atom you have. (The overall charge atom you have. (The overall charge must equal zero!!)must equal zero!!)

EXAMPLE: Write the chemical EXAMPLE: Write the chemical formula for the compound containing formula for the compound containing Al and Br.Al and Br.

#1 – determine the charges#1 – determine the charges

AlAl+3+3 Br Br-1-1

#2 – cross the charges.#2 – cross the charges.

AlAl+3+3 Br Br-1-1

#3 – Write the formula, simplify if #3 – Write the formula, simplify if needed needed

AlBrAlBr33

31

Try this one…Try this one…

Write the chemical formula for the Write the chemical formula for the compound containing Mg and Scompound containing Mg and S

#1 – determine the charges#1 – determine the charges

MgMg+2+2 S S-2-2

#2 – cross the charges.#2 – cross the charges.

MgMg+2+2 S S-2-2

#3 – Write the formula, simplify if #3 – Write the formula, simplify if needed needed

MgMg22SS22

MgSMgS

22

Ionic Compounds with Ionic Compounds with Polyatomic IonsPolyatomic Ions

#1 – name the 1st part of the compound#1 – name the 1st part of the compound #2 – name the 2nd part#2 – name the 2nd part If it is a polyatomic ion, If it is a polyatomic ion, DO NOTDO NOT change change

the endingthe ending If it is a nonmetal, change to –ide.If it is a nonmetal, change to –ide. Examples:Examples: CaCOCaCO33

NaNa33SOSO44

(NH(NH44))22SS

Calcium carbonateCalcium carbonate Sodium sulfateSodium sulfate Ammonium sulfideAmmonium sulfide

Writing Formulas:Writing Formulas: Same rules apply, except if the polyatomic Same rules apply, except if the polyatomic

ion gets a subscript you MUST use ion gets a subscript you MUST use parentheses around it.parentheses around it.

Example:Example: Write the formula for sodium hydroxide.Write the formula for sodium hydroxide.

NaNa+1+1 OH OH-1-1

NaOHNaOH

11

Writing Formulas for Writing Formulas for Polyatomic CompoundsPolyatomic Compounds

Calcium phosphateCalcium phosphate

CaCa+2+2 PO PO44-3-3

CaCa33(PO(PO44))22

23

Aluminum nitriteAluminum nitrite

AlAl+3+3 NO NO22-1-1

Al(NOAl(NO22))33

31

Homework

Page 221

Problems 19, 20, 21 and 22

Page 233

Problem 83

Compounds Containing Compounds Containing Metals with Variable Metals with Variable

ChargesCharges

Variable ChargesVariable Charges(Transition Metals)(Transition Metals)

Metals in Group 1, Group 2, Zinc Metals in Group 1, Group 2, Zinc (+2), Silver (+1) and Aluminum only (+2), Silver (+1) and Aluminum only have one charge. have one charge.

The rest have The rest have variablevariable charges so charges so we have to we have to telltell what charge the ion what charge the ion has in our compound when we name has in our compound when we name it.it.

NamingNaming

#1 – Name the metal.#1 – Name the metal. #2 – Add a roman numeral #2 – Add a roman numeral telling telling

the charge on the metal in the charge on the metal in parentheses.parentheses.

I-1 II-2 III-3 IV-4 V-5 VI-6 VII-7I-1 II-2 III-3 IV-4 V-5 VI-6 VII-7 #3 – Name the negative ion #3 – Name the negative ion as as

before.before.

ExampleExample

CrOCrO O is a -2 chargeO is a -2 charge To make a neutral compound, Cr To make a neutral compound, Cr

must be a +2.must be a +2. Chromium (II) oxideChromium (II) oxide

FeClFeCl33 Cl is a -1 chargeCl is a -1 charge There are 3 chlorine ions There are 3 chlorine ions -3 -3 The ONE Fe must be a +3The ONE Fe must be a +3 Iron (III) chlorideIron (III) chloride

CoCOCoCO33

Carbonate is a -2Carbonate is a -2 Co is a +2Co is a +2 Cobalt (II) carbonateCobalt (II) carbonate

NiNi33(PO(PO44))22

Phosphate = -3 x 2 = -6Phosphate = -3 x 2 = -6 There are 3 nickel atoms so each one There are 3 nickel atoms so each one

= +2 to equal +6= +2 to equal +6 Nickel (II) phosphateNickel (II) phosphate

Mn(SOMn(SO44))22

Sulfate is -2, there are two Sulfate is -2, there are two -4 -4 so the ONE Manganese = +4so the ONE Manganese = +4 Manganese (IV) sulfateManganese (IV) sulfate

Writing formulas:Writing formulas:

Rules are the same as before.Rules are the same as before.

copper (III) oxidecopper (III) oxide

CuCu+3+3 O O-2-2

CuCu22OO33

32

Manganese (IV) sulfideManganese (IV) sulfide

MnMn+4+4 S S-2-2

MnMn22SS44

MnSMnS22

42

Iron (II) nitrateIron (II) nitrate

FeFe+2+2 NO NO33-1-1

Fe(NOFe(NO33))22

21

Classwork

Page 223

Problems 28, 29, 30, 31 and 32

Page 233

Problem 82