Naming CompoundsNaming CompoundsWriting FormulasWriting Formulas

and Equationsand Equations

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DHMO is dihydrogen monoxide.

Evaluate the following link and decide if this potentially dangerous chemical should be prohibited.

www.dhmo.org

The chemical formula represents the composition of The chemical formula represents the composition of each molecule. each molecule.

In writing the chemical formula, in almost all cases In writing the chemical formula, in almost all cases the element farthest to the left of the periodic table is the element farthest to the left of the periodic table is written firstwritten first. .

So for example the chemical formula of a compound So for example the chemical formula of a compound that contains one sulfur atom and six fluorine atoms that contains one sulfur atom and six fluorine atoms is SFis SF66. .

If the two elements are in the same group, the If the two elements are in the same group, the symbol of the element of that is lower in the group symbol of the element of that is lower in the group (i.e. heavier) is written first e.g. IF(i.e. heavier) is written first e.g. IF33..

Naming Compounds

Ionic compounds are combinations of positive Ionic compounds are combinations of positive

and negative ions.and negative ions. In writing the chemical formula the In writing the chemical formula the positive ion positive ion is is

written firstwritten first, It is then followed by the name of the , It is then followed by the name of the

negative ion. negative ion. Monatomic anions end in Monatomic anions end in ide.ide. Special endings Special endings

apply for polyatomic ionsapply for polyatomic ions ExamplesExamples

NaCl Sodium chlorNaCl Sodium chlorideide

BaFBaF22 Barium Fluor Barium Fluorideide

ZnO Zinc OxZnO Zinc Oxideide

Naming Ionic Compounds

Names of Polyatomic Names of Polyatomic Ions with OxygenIons with Oxygen

Polyatomic ions Polyatomic ions usually contain usually contain oxygen in addition oxygen in addition to another element. to another element. Normally they have Normally they have a a negative chargenegative charge.  .  They end in either They end in either ""ateate" or "" or "iteite" " depending on the depending on the number of oxygen number of oxygen atoms present.atoms present.

ClOClO-- hypohypochlorchloriteite

ClOClO22-- chlorchloriteite

ClOClO33-- chlorchlorateate

ClOClO44-- perperchlorchlorateate

NONO22-- NitrNitriteite  

NONO33-- NitrNitrateate  

POPO333-3- phosphphosphiteite  

POPO443-3- phosphphosphateate  

SOSO332-2-

SOSO442-2-

sulfsulfiteite  

sulfsulfateate  

Polyatomic Ion -- Polyatomic Ion -- ExceptionsExceptions

Most polyatomic ions contain oxygenMost polyatomic ions contain oxygen

Their names end in “Their names end in “iteite” or “” or “ateate”.”.

There are several exceptionsThere are several exceptionsOHOH-- hydroxide hydroxide

CNCN-- cyanide cyanide

SCNSCN- - thiocyanate thiocyanate

Elements with Multiple CationsElements with Multiple Cations

When an element can form more than one cation a When an element can form more than one cation a Roman numeral is used to distinguish the oxidation Roman numeral is used to distinguish the oxidation state of the compound.state of the compound.Iron, Tin, Lead, Copper, and are common elements with Iron, Tin, Lead, Copper, and are common elements with more than one cation. more than one cation. Examples Examples

1.1. PbSOPbSO44  =  lead  =  lead (II)(II) sulfate sulfate   This compound is formed   This compound is formed from Pbfrom Pb2+2+ and  SO and  SO44

2-2-

2.2. Pb(SOPb(SO44))22 =  lead  =  lead (IV) (IV) sulfatesulfate   This compound is formed   This compound is formed from Pbfrom Pb4+4+ and  SO and  SO44

2-2-

3.3. Fe(OH)Fe(OH)22  =  iron   =  iron (II)(II) hydroxide hydroxide   This compound is   This compound is formed from Feformed from Fe2+2+ and  OH and  OH--  

4.4. Fe(OH)Fe(OH)33  =  iron  =  iron (III) (III)  hydroxide hydroxide      This compound is   This compound is formed from Fe formed from Fe3+3+ and  OH and  OH--

Examples of Ionic CompoundsExamples of Ionic Compounds

1.1. NaClNaCl == Sodium chlorSodium chlorideide

2.2. ZnFZnF22 == Zinc fluorZinc fluorideide

3.3. KOHKOH == Potassium hydroxPotassium hydroxideide

4.4. Ca(NOCa(NO33))22 == Calcium nitrCalcium nitrateate

5.5. BaSOBaSO33 == Barium SulfBarium Sulfiteite

6.6. AlAl22(SO(SO44) ) 3 3 == Aluminum sulfAluminum sulfateate

7.7. CaCa33(PO(PO33))22 == Calcium phosphiteCalcium phosphite

8.8. NHNH44ClCl == AmmonAmmoniumium chlor chlorideide

9.9. (NH(NH44))22COCO33 == Ammonium carbonateAmmonium carbonate

When naming covalent compounds, the name When naming covalent compounds, the name of the first element in the formula is of the first element in the formula is unchanged.unchanged.

The suffix The suffix “-ide”“-ide” is added to the second is added to the second element.element.

Often a prefix to the name of the second Often a prefix to the name of the second element indicates the number of the element element indicates the number of the element in the compoundin the compound

Examples:Examples:

SFSF66 – sulfur hexafluoride – sulfur hexafluoridePP44OO1010 – tetraphosphorous decoxide – tetraphosphorous decoxideCO – carbon monoxideCO – carbon monoxideCOCO22 – carbon dioxide – carbon dioxide

Naming Covalent Compounds

Covalent molecules with Covalent molecules with multiple possibilitiesmultiple possibilities

A Roman Numeral is used to indicate the state A Roman Numeral is used to indicate the state of the more positive elementof the more positive element

ExamplesExamples

1.1. NN22O   =  Nitrogen (I) oxideO   =  Nitrogen (I) oxide    Since oxygen has a   Since oxygen has a

2- charge, the nitrogen must be 1+ to  balance 2- charge, the nitrogen must be 1+ to  balance the charges.    Also known asthe charges.    Also known as didinitrogen nitrogen monomonoxidexide

2.2. NN22OO33 =  Nitrogen (III) oxide =  Nitrogen (III) oxide    Since oxygen has a    Since oxygen has a

2- charge, the nitrogen must be 3+ to balance the 2- charge, the nitrogen must be 3+ to balance the charges  Also  known as charges  Also  known as didinitrogen nitrogen tritrioxideoxide

The binary compounds of hydrogen are The binary compounds of hydrogen are special cases. They were discovered before special cases. They were discovered before a convention was adopted and hence their a convention was adopted and hence their original names have stayed.original names have stayed.

Hydrogen forms binary compounds with almost all non-metals except the noble gases. Examples

HF - hydrogen fluorideHCl - hydrogen chloride H2S - hydrogen sulfide

Water H2O is not called dihydrogen monoxide

Binary compounds of Hydrogen

When many hydrogen compounds are dissolve in When many hydrogen compounds are dissolve in water they take on the form of an acid. Special rules water they take on the form of an acid. Special rules apply to acids. The apply to acids. The “ite”“ite” suffix becomes suffix becomes “ous”“ous” and and the the “ate”“ate” suffix becomes suffix becomes “ic”“ic”

Acids

HClHCl HydroHydrochlorchloricic AcidAcid Cl-Cl- ChlorChlorideide

HNOHNO22 NitrNitrous Acidous Acid NONO22-- NitrNitriteite

HNOHNO33 NitrNitricic AcidAcid NONO33-- NitrNitrateate

HH22SOSO33 SulfurSulfurousous AcidAcid SOSO332-2- SulfSulfiteite

HH22SOSO44 SulfurSulfuricic AcidAcid SOSO442-2- SulfSulfateate

HH33POPO33 PhosphorPhosphorousous AcidAcid POPO333-3- PhosphPhosphiteite

HH33POPO44 PhosphorPhosphoricic AcidAcid POPO443-3- PhosphPhosphateate

HH22COCO33 CarbonCarbonicic AcidAcid COCO332-2- CarbonCarbonateate

Writing Formulas for Ionic Writing Formulas for Ionic CompoundsCompounds

Write the positive ion (cation) first, then the Write the positive ion (cation) first, then the negative ion.negative ion.The positive charges must balance the negative The positive charges must balance the negative charges. charges. Use subscripts to show how many times each Use subscripts to show how many times each ion must appear in order for the charges to ion must appear in order for the charges to balance. A subscript is not used if the ion balance. A subscript is not used if the ion appears only onceappears only onceUse parenthesis around polyatomic ions that Use parenthesis around polyatomic ions that appear more than once in the formulaappear more than once in the formula

ExamplesExamples

1.1. NaNa++ and Cl and Cl-- = NaCl = NaCl

2.2. ZnZn2+2+ and Br and Br-- = ZnBr = ZnBr22

3.3. KK++ and OH and OH- - = KOH = KOH

4.4. CaCa2+2+ and OH and OH- - = Ca(OH)= Ca(OH)22

5.5. FeFe2+2+ and SO and SO442-2- = FeSO = FeSO44

6.6. FeFe3+ 3+ and SO and SO442-2- = Fe = Fe22(SO(SO44) ) 33

7.7. CaCa2 + 2 + and PO and PO443-3- = Ca = Ca33(PO(PO44))22

8.8. NHNH44++ and Cl and Cl-- = NH = NH44ClCl

9.9. NHNH44++ and CO and CO33

2-2- = (NH = (NH44))22COCO33

Chemical ReactionsChemical Reactions

Elements and compounds frequently Elements and compounds frequently undergo chemical reactions to form new undergo chemical reactions to form new substancessubstances

In a chemical reaction, chemical bonds are In a chemical reaction, chemical bonds are frequently broken and new chemical frequently broken and new chemical bonds are formedbonds are formed

Atoms are neither created nor destroyed in Atoms are neither created nor destroyed in an ordinary chemical changean ordinary chemical change

Chemical ReactionsChemical Reactions

A balanced chemical reaction is used to A balanced chemical reaction is used to describe the process that occurs in a describe the process that occurs in a chemical change.chemical change.

For example: Zinc reacts with hydrochloric For example: Zinc reacts with hydrochloric acid to produce zinc chloride and acid to produce zinc chloride and hydrogen gas. hydrogen gas.

This chemical reaction could be written asThis chemical reaction could be written as

Zn + 2 HCl Zn + 2 HCl ZnCl ZnCl22 + H + H22

Reactants and ProductsReactants and Products

In the chemical reactionIn the chemical reaction

Zn + 2 HCl Zn + 2 HCl ZnCl ZnCl22 + H + H22

ReactantsReactants Products Products

This shorthand way of describing a chemical This shorthand way of describing a chemical reaction is known as a reaction is known as a chemical equationchemical equation

The starting materials are shown on the left and The starting materials are shown on the left and are known as are known as reactantsreactants

The substances formed are shown on the right The substances formed are shown on the right and are known as the and are known as the productsproducts

Balancing a Chemical ReactionBalancing a Chemical Reaction

A proper chemical reaction must be A proper chemical reaction must be balancedbalanced

Zn + 2 HCl Zn + 2 HCl ZnCl ZnCl22 + H + H22

ReactantsReactants Products Products

Each element must appear on both sides Each element must appear on both sides of the arrow and equal number of timesof the arrow and equal number of timesChemical reactions can be balanced by Chemical reactions can be balanced by inserting numbers in front of formulas.inserting numbers in front of formulas.These numbers are called These numbers are called coefficientscoefficients

Balancing Chemical ReactionsBalancing Chemical ReactionsMost simple equations can be balanced by Most simple equations can be balanced by inspectioninspectionExample: Balance the following equationExample: Balance the following equation

BaClBaCl22 + K + K33POPO44 Ba Ba33 (PO (PO44))22 + KCl + KCl

• There are There are 3 Ba3 Ba on the right so we need coefficient of on the right so we need coefficient of 33 in front of in front of BaClBaCl22

• There are There are 2 PO2 PO44 on the right so we need a coefficient of on the right so we need a coefficient of 22 in front of in front of KK33POPO44..

• This leaves This leaves 6 K6 K on the left so we need a coefficient of on the left so we need a coefficient of 66 in front of the in front of the KCl KCl on the righton the right

The balanced equation isThe balanced equation is

3 3 BaClBaCl22 + + 2 2 KK33POPO44 Ba Ba33 (PO (PO44))22 + + 6 6 KClKCl

Balancing Chemical ReactionsBalancing Chemical Reactions

An equation is balanced when there are the same An equation is balanced when there are the same number and kind of atoms on both sides of the number and kind of atoms on both sides of the arrowarrow

3 3 BaClBaCl22 + + 2 2 KK33POPO44 Ba Ba33(PO(PO44))22 + + 6 6 KClKCl

Reactants (Left)Reactants (Left) Products (Right)Products (Right) Ba Ba 33 Ba Ba 33

Cl Cl 33 x x 22 = 6 = 6 Cl Cl 66

K K 22 x x 33 = 6 = 6 K K 66

P P 22 P P 22

O O 22 x x 44 = 8 = 8 OO 2 2 x x 44 = 8 = 8

State SymbolsState Symbols

State symbols are often added to chemical equations. State symbols are often added to chemical equations.

CaCOCaCO33 (s)(s) + 2 HCl + 2 HCl (aq)(aq) CaCl CaCl22 (aq)(aq) + CO + CO22 (g)(g) + H + H22O O (l)(l)

Symbols Symbols

(s)(s) SolidSolid

(l)(l) LiquidLiquid

(g)(g) GasGas

(aq)(aq) Aqueous (Water Solution)Aqueous (Water Solution)

Types of ReactionsTypes of Reactions

There are many kinds of chemical There are many kinds of chemical reactions that occur. Some are very reactions that occur. Some are very simple while others are very complex simple while others are very complex and may occur in multiple steps.and may occur in multiple steps.A number of reactions conform to A number of reactions conform to some relatively simple patternssome relatively simple patternsUnderstanding and identifying these Understanding and identifying these patterns can be helpful in predicting patterns can be helpful in predicting the products of similar reactionsthe products of similar reactions

Direct CombinationDirect Combination

In a direct combination, two elements or In a direct combination, two elements or compounds combine to form a more compounds combine to form a more complicated productcomplicated product

ExamplesExamples

CaO + COCaO + CO22 CaCO CaCO33

2 H2 H22 + O + O22 2 H 2 H22OO

FeClFeCl22 + Cl + Cl22 FeCl FeCl33

NN22 + O + O22 2 NO 2 NO

DecompositionDecomposition

In a dcecomposition, a single compound In a dcecomposition, a single compound is broken down into two or more simplier is broken down into two or more simplier substancessubstances

ExamplesExamples

2 KClO2 KClO33 2 KCl + 3 O 2 KCl + 3 O22

ZnCOZnCO3 3 ZnO + CO ZnO + CO22

Cu(OH)Cu(OH)22 CuO + H CuO + H22OO

Single ReplacementSingle Replacement

In a single replacement, one substance In a single replacement, one substance (usually an element) takes the place of (usually an element) takes the place of another in a compoundanother in a compound

ExamplesExamples

ZnZn + + HH22SOSO44 ZnZnSOSO44 + + HH22

ClCl22 + 2 K+ 2 KBrBr 2 K 2 KClCl + + BrBr22

MgMg + + CuCuClCl22 MgMgClCl22 + + CuCu

Double ReplacementDouble Replacement

In a double replacement, two substances In a double replacement, two substances exchange places in their respective exchange places in their respective compoundscompounds

ExamplesExamples

AgAgNONO33 + + NaNaClCl Ag AgClCl + + NaNaNONO33

3 3 CaCaClCl22 + 2 + 2 KK33POPO44 CaCa33(PO(PO44))22 + 6 + 6KKCl Cl

BaBaClCl22 + + NaNa22SOSO44 BaBaSOSO44 + 2 + 2NaNaCl Cl

Diatomic MoleculesDiatomic Molecules

Certain elements Certain elements exist as diatomic exist as diatomic molecules in naturemolecules in nature

HH22 HHydrogenydrogen

NN22 NNitrogenitrogen

FF22 FFluorineluorine

OO22 OOxygenxygen

II22 IIodineodine

ClCl22 CChlorinehlorine

BrBr22 BBromineromine

Diatomic MoleculesDiatomic Molecules

Certain elements Certain elements exist as diatomic exist as diatomic molecules in naturemolecules in nature

HH22 HHydrogenydrogen HHaveave

NN22 NNitrogenitrogen NNoo

FF22 FFluorineluorine FFearear

OO22 OOxygenxygen OOff

II22 IIodineodine IIcece

ClCl22 CChlorinehlorine CColdold

BrBr22 BBromineromine BBeereer