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Naming CompoundsNaming CompoundsWriting FormulasWriting Formulas
and Equationsand Equations
Ban DHMO?
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