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Chapter 5. Molecules and Compounds. Homework. Assigned Problems (odd numbers only) Required “Problems” 23-79 (odd) “Cumulative Problems” 81-97 (odd) Highlight Problems “Highlight Problems” 99, 101 (odd). Compounds Display Constant Composition. - PowerPoint PPT Presentation
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HomeworkHomework Assigned Problems (odd numbers only)Assigned Problems (odd numbers only)
RequiredRequired ““Problems” 23-79 (odd)Problems” 23-79 (odd)
““Cumulative Problems” 81-97 (odd)Cumulative Problems” 81-97 (odd)
Highlight ProblemsHighlight Problems ““Highlight Problems” 99, 101 (odd)Highlight Problems” 99, 101 (odd)
Compounds Display Constant CompositionCompounds Display Constant Composition
Compounds are pure substances consisting of Compounds are pure substances consisting of two or more elements held together by a two or more elements held together by a chemical bond chemical bond
A compound can be broken into its elements by A compound can be broken into its elements by a chemical processa chemical process
The percentage of each element in a specific The percentage of each element in a specific compound does not varycompound does not vary The Law of Definite Proportions The Law of Definite Proportions (Constant (Constant
Composition): In a pure compound, the elements are Composition): In a pure compound, the elements are always present in the same definite proportions by always present in the same definite proportions by massmass
Compounds Display Constant CompositionCompounds Display Constant Composition
Example:Example: Two samples of ammonia gas with different sample Two samples of ammonia gas with different sample
massesmasses Upon decomposition, the mass ratios of nitrogen to Upon decomposition, the mass ratios of nitrogen to
hydrogen are the samehydrogen are the same
Sample 1: Sample 2:4.63g 0.327
g5131
.4.62
g 0.356
g6441
.
Chemical Formulas: Chemical Formulas: How to Represent CompoundsHow to Represent Compounds
Chemical formulas are a concise way of stating Chemical formulas are a concise way of stating a specific chemical compound’s compositiona specific chemical compound’s composition
The notation contains the symbols of the The notation contains the symbols of the elements present and the subscripts to indicate elements present and the subscripts to indicate the number of atoms per element in a structural the number of atoms per element in a structural unit of the compoundunit of the compound
Aspirin’s chemical formula is C9H8O4
Element symbols
21 atoms are present:9 carbon atoms, 8 hydrogen atoms, and 4 oxygen atomsRatio of C to H to O is 9:8:4
subscripts
Chemical Formulas: Chemical Formulas: How to Represent CompoundsHow to Represent Compounds
All pure samples of a compound have the same All pure samples of a compound have the same compositioncomposition
If only one atom is present in a molecule, the If only one atom is present in a molecule, the subscript “1” is omittedsubscript “1” is omitted
Follow the capitalization rules for elemental Follow the capitalization rules for elemental symbolssymbols
When writing formulas, list the metal or most When writing formulas, list the metal or most metallic element firstmetallic element first
Co is the symbol for cobaltCO is the formula for carbon monoxide
sodium chloride NaCl not ClNacarbon dioxide CO2 not O2C
Chemical Formulas: Chemical Formulas: How to Represent CompoundsHow to Represent Compounds
If a chemical formula contains groups of atoms in parentheses, the subscript following the parentheses indicates the number polyatomic units in the formula
Number of atoms is determined by multiplying the subscript outside the parenthesis by the subscript for every atom inside the parenthesis
Composition is 1 Mg atom, 2 N atoms, 6 O atoms
Polyatomic ion
A Molecular View ofA Molecular View ofElements and CompoundsElements and Compounds
Pure substancesPure substances ElementsElements
AtomicAtomic MolecularMolecular
CompoundsCompounds Ionic Ionic MolecularMolecular
Elements and CompoundsElements and Compounds Elements are substances that cannot be decomposed into simpler Elements are substances that cannot be decomposed into simpler
substancessubstances Each element is composed of only one type of atomEach element is composed of only one type of atom Most elements are Most elements are atomicatomic elements elements and exist as single atoms and exist as single atoms
(monatomic) (monatomic) Molecular elements Molecular elements are found naturally as two or more of the same are found naturally as two or more of the same
type of atom bound together (diatomic)type of atom bound together (diatomic)
Elements and CompoundsElements and Compounds
A compound can be decomposed into two or more simpler A compound can be decomposed into two or more simpler substancessubstances
The ultimate breakdown products are elementsThe ultimate breakdown products are elements Two types of compoundsTwo types of compounds
MolecularMolecular IonicIonic
Molecular CompoundsMolecular Compounds
A molecule is a group of two or more atoms A molecule is a group of two or more atoms bound together as a unitbound together as a unit
A A molecular compound molecular compound involves a bond between involves a bond between two or more nonmetalstwo or more nonmetals
Bonds occur between different or identical Bonds occur between different or identical atomsatoms
The individual molecule is the smallest particle The individual molecule is the smallest particle that can exist as a stable, independent unit of that can exist as a stable, independent unit of the compoundthe compound
Molecular (Covalent) CompoundsMolecular (Covalent) Compounds Molecular compounds are compounds composed of Molecular compounds are compounds composed of
molecules that exist as the individual structural unit molecules that exist as the individual structural unit The simplest molecule contains two atoms (diatomic). The simplest molecule contains two atoms (diatomic).
They can be the same or different atomsThey can be the same or different atoms Next in complexity are triatomic and tetraatomicNext in complexity are triatomic and tetraatomic
COcarbon monooxide
H2Owater
A diatomic molecule A triatomic molecule
O2
oxygen
A diatomic molecule
O3
ozone
A triatomic molecule
Ionic CompoundsIonic Compounds
Ionic compounds Ionic compounds are care compounds which ompounds which are held together by the attraction of are held together by the attraction of positive and negative ionspositive and negative ions
Solid crystalsSolid crystals formed by a very ordered formed by a very ordered packing of oppositely charged ionspacking of oppositely charged ions
Most ionic compounds are composed of a Most ionic compounds are composed of a metal and a nonmetalmetal and a nonmetal
High melting temperaturesHigh melting temperatures
Fig4_21a
Cl–
Cl–
Cl–
Cl–
Cl–
Cl–
Na+
Na+
Na+
Na+
Na+
Na+
Ionic CompoundsIonic Compounds SolidsSolids They do not exist as single They do not exist as single
moleculesmolecules The chemical formula The chemical formula
represents the simplest ratio represents the simplest ratio that these atoms combine that these atoms combine togethertogether
Held strongly together, these Held strongly together, these ions are packed together into a ions are packed together into a “lattice” “lattice”
Each NaEach Na++ ion is surrounded on ion is surrounded on each side by Cleach side by Cl-- ions ions
Each ClEach Cl-- ion is surrounded on ion is surrounded on each side by Naeach side by Na++ ions ions
Formula unit = NaCl
Ionic CompoundsIonic Compoundsvs. Molecular Compoundsvs. Molecular Compounds
For molecular For molecular compounds, the compounds, the chemical formulas chemical formulas give the composition give the composition of the moleculesof the molecules
For ionic compounds, For ionic compounds, the chemical formulas the chemical formulas give the ion ratio give the ion ratio within the compoundwithin the compound
Writing Formulas for Ionic Compounds Writing Formulas for Ionic Compounds (Charge Balance in Ionic Compounds)(Charge Balance in Ionic Compounds)
Binary ionic compounds are composed of Binary ionic compounds are composed of only two elements (metal and nonmetal)only two elements (metal and nonmetal) The symbol of the cation always The symbol of the cation always
precedes the symbol of the anionprecedes the symbol of the anion The sum of the positive charges (cation) The sum of the positive charges (cation)
must equal the sum of the negative must equal the sum of the negative charges (anion) charges (anion)
Net charge is zero (charge-neutral)Net charge is zero (charge-neutral) Subscripts written as whole numbers Subscripts written as whole numbers
indicate the number of each ion in the indicate the number of each ion in the formula unitformula unit
Writing Formulas for Ionic Compounds Writing Formulas for Ionic Compounds Subscripts in FormulasSubscripts in Formulas
Sodium ChlorideSodium Chloride Formed from Formed from
sodium and sodium and chlorine atomschlorine atoms
An ionic bond An ionic bond forms consisting of forms consisting of a sodium ion a sodium ion (+ charge) and a (+ charge) and a chloride ion chloride ion (- charge)(- charge)
Each sodium loses Each sodium loses one electron to one electron to achieve an octet achieve an octet
Each chlorine atom Each chlorine atom gains one electron gains one electron to achieve an octetto achieve an octet
Formula is Formula is NaClNaCl
Writing Formulas for Ionic Compounds Writing Formulas for Ionic Compounds Subscripts in FormulasSubscripts in Formulas
Magnesium ChlorideMagnesium Chloride Formed from Formed from
magnesium and magnesium and two chlorinestwo chlorines
An ionic bond An ionic bond forms consisting of forms consisting of a magnesium ion a magnesium ion (2+ charge) and (2+ charge) and two chloride ions two chloride ions (- charge (- charge each)each)
Each magnesium Each magnesium loses two electrons loses two electrons to achieve an octet to achieve an octet
Each chlorine atom Each chlorine atom gains one electron to gains one electron to achieve an octetachieve an octet
Formula is Formula is MgClMgCl22
Writing Ionic Formulas for Writing Ionic Formulas for Ionic ChargesIonic Charges
Subscripts in a formula represent the number of positive and Subscripts in a formula represent the number of positive and negative ionsnegative ions Write the formula for the ionic compound containing NaWrite the formula for the ionic compound containing Na+ + and Nand N3-3-
••
••
• •
• •
• •
• •
Na•
Na•
N
Na+
Na+
Na+
N • • •
• •
• •
• •
• • • •
3-
Net charge: 3(1+) + 1(3-)=0Net charge: 3(1+) + 1(3-)=0Formula:Formula: NaNa33NN
Na•
Each loses 1eEach loses 1e--
Gains 3eGains 3e--
Naming Ionic CompoundsNaming Ionic Compounds
For ionic compounds containing two elements:For ionic compounds containing two elements: Compounds containing a metal and a Compounds containing a metal and a
nonmetal are called nonmetal are called binary ionic compoundsbinary ionic compounds Two types of metals:Two types of metals:
Single Cation Metals: Form one positive ionSingle Cation Metals: Form one positive ion Multiple Cation Metals: Form more than one Multiple Cation Metals: Form more than one
positive ionpositive ion
The systematic naming uses the name of the The systematic naming uses the name of the cation first, followed by the name of the anioncation first, followed by the name of the anion
Subscripts in the formula are not included in Subscripts in the formula are not included in the namethe name
Types of Metal IonsTypes of Metal Ions
Single Cation Metals (Type I)Single Cation Metals (Type I) Form only one type of ion (one possible Form only one type of ion (one possible
charge)charge) Main group metals in groups IA, IIA, and Main group metals in groups IA, IIA, and
some IIIAsome IIIA e.g. Sodium only forms one ion e.g. Sodium only forms one ion (Na(Na++)) in in
chemical reactionschemical reactions Determine charge by position on the Determine charge by position on the
periodic tableperiodic table (also see table 5.3 on page (also see table 5.3 on page 136)136)
Types of Metal IonsTypes of Metal Ions
Single Cation Metals (Type I)Single Cation Metals (Type I) Form only one type of ion (one possible charge)Form only one type of ion (one possible charge) Main group metals in groups IA, IIA, and some IIIAMain group metals in groups IA, IIA, and some IIIA e.g. Sodium only forms one ion e.g. Sodium only forms one ion (Na(Na++)) in chemical in chemical
reactionsreactions Determine charge by position on the Determine charge by position on the periodic tableperiodic table
(also see table 5.3 on page 136)(also see table 5.3 on page 136)
Types of Metal IonsTypes of Metal Ions Multiple Cation Metals (Type II) Multiple Cation Metals (Type II)
Form two or more types of ions (variable Form two or more types of ions (variable possible charge)possible charge)
Transition metals in groups 3B to 12B, and Transition metals in groups 3B to 12B, and some 4A and 5Asome 4A and 5A
For example, iron forms two ions (FeFor example, iron forms two ions (Fe2+ 2+ and and FeFe3+3+) in chemical reactions) in chemical reactions
Determine charge by the “stock system” for Determine charge by the “stock system” for naming ions naming ions
The The metal namemetal name followed by a followed by a Roman Roman numeralnumeral in parentheses to indicate its in parentheses to indicate its charge (see table 5.4 on page 136)charge (see table 5.4 on page 136)
Types of Metal IonsTypes of Metal Ions Multiple Cation Metals (Type II) Multiple Cation Metals (Type II)
Form two or more types of ions (variable possible charge)Form two or more types of ions (variable possible charge) Transition metals in groups 3B to 12B, and some 4A and 5ATransition metals in groups 3B to 12B, and some 4A and 5A For example, iron forms two ions (FeFor example, iron forms two ions (Fe2+ 2+ and Feand Fe3+3+) in chemical ) in chemical
reactionsreactions Determine charge by the “stock system” for naming ions Determine charge by the “stock system” for naming ions The The metal namemetal name followed by a followed by a Roman numeralRoman numeral in parentheses to in parentheses to
indicate its charge (see table 5.4 on page 136)indicate its charge (see table 5.4 on page 136)
Naming Type I Binary Ionic CompoundsNaming Type I Binary Ionic Compounds
Compounds which contain a positively Compounds which contain a positively charged metallic ion and a negatively charged charged metallic ion and a negatively charged nonmetallic ionnonmetallic ion
Name metal Name metal cationcation first, name nonmetal first, name nonmetal anionanion secondsecond
Single metal cation name is the Single metal cation name is the metal name metal name only, only, drop the word “ion”drop the word “ion”
Nonmetal anion named by changing the Nonmetal anion named by changing the ending on the nonmetal name to -ending on the nonmetal name to -ideide
Name of metal__base name of nonmetal + -ide
Naming Type I Ionic CompoundsNaming Type I Ionic Compounds
NaINaI Sodium IodSodium Iodideide
CaFCaF22
Calcium FluorCalcium Fluorideide LiLi22OO
Lithium OxLithium Oxideide AgClAgCl
Silver ChlorSilver Chlorideide
KClPotassium Chloride
Na3PSodium Phosphide
Rb2SRubidium Sulfide
Mg3N2
Magnesium Nitride
Naming Type II Binary Ionic CompoundsNaming Type II Binary Ionic CompoundsMultiple Cation Metal CompoundsMultiple Cation Metal Compounds
Metal listed first in formula & name (same Metal listed first in formula & name (same order as for Type I compounds)order as for Type I compounds)
Determine metal cation charge from the Determine metal cation charge from the anion chargeanion charge
Common multiple cations in Table 5.4, Common multiple cations in Table 5.4, page 136page 136
Naming Type II Binary Ionic CompoundsNaming Type II Binary Ionic CompoundsMultiple Cation Metal CompoundsMultiple Cation Metal Compounds
Use the Use the metal namemetal name (cation) first, followed (cation) first, followed by a by a Roman numeralRoman numeral in parentheses to in parentheses to indicate its chargeindicate its charge
Nonmetal anion named by changing the Nonmetal anion named by changing the ending on the nonmetal name to -ending on the nonmetal name to -ideide
Name of metal (charge of metal)______base name of nonmetal + -idecation anion
Naming Type II Binary Ionic CompoundsNaming Type II Binary Ionic Compounds
FeIFeI33
1(1(??)+3(-1)=0)+3(-1)=0 Iron Iron (III)(III) Iod Iodideide
CuCu22OO 2(2(??)+1(-2)=0)+1(-2)=0 Copper Copper (I)(I) Ox Oxideide
SnBrSnBr22
1(1(??)+2(-1)=0)+2(-1)=0 Tin Tin (II)(II) Brom Bromideide
Naming Type II Binary Ionic CompoundsNaming Type II Binary Ionic Compounds Determining the Charge of the Cation from the AnionDetermining the Charge of the Cation from the Anion
Determine the charge of Cu in CuDetermine the charge of Cu in Cu22OOWrite the name of the compoundWrite the name of the compound1)1)Determine theDetermine the charge of the cation from charge of the cation from
the anionthe anion CuCu22O - the nonmetal anion is O, since it is O - the nonmetal anion is O, since it is
in Group 6A, its charge is in Group 6A, its charge is 2-2- Since there are 2 Cu ions in the formula Since there are 2 Cu ions in the formula
and the total positive charge is and the total positive charge is 2+2+, divide , divide by the by the number of cationsnumber of cations so each Cu has so each Cu has a a 1+1+ charge charge
Naming Type II Binary Ionic CompoundsNaming Type II Binary Ionic Compounds Determining the Charge of the Cation from the AnionDetermining the Charge of the Cation from the Anion
2)2) Name the cation by its element name and Name the cation by its element name and use a Roman numeral in parenthesis to use a Roman numeral in parenthesis to indicate its chargeindicate its charge
Copper (I)Copper (I)3)3) Name the anion by changing the last part of Name the anion by changing the last part of
its element name to –its element name to –ideide OxygenOxygen4)4) Write the name of the cation first and the Write the name of the cation first and the
name of the anion secondname of the anion second
copper (I) oxide
oxide
Naming Type II Binary Ionic CompoundsNaming Type II Binary Ionic Compounds Determining the Charge of the Cation from the AnionDetermining the Charge of the Cation from the Anion
• SnISnI44
• 1(?)+4(-1)=01(?)+4(-1)=0• Tin Tin (IV)(IV) iod iodideide
• HgOHgO• 1(?)+1(-2)=01(?)+1(-2)=0• Mercury Mercury (II)(II) Ox Oxideide
• MnClMnCl22• 1(?)+2(-1)=01(?)+2(-1)=0• Manganese Manganese (II) (II) ChlorChlorideide
Writing Formulas from the Name of Writing Formulas from the Name of an Ionic Compoundan Ionic Compound
Usually involves a metal and a nonmetalUsually involves a metal and a nonmetal
1)1) Identify the cation and the anionIdentify the cation and the anion
2)2) Balance the charges to write the formulaBalance the charges to write the formula If it is a multiple cation metal, the Roman If it is a multiple cation metal, the Roman
numeral determines the charge of the numeral determines the charge of the cationcation
3)3) When writing the formula, take the name of When writing the formula, take the name of the cation first, followed by the name of the the cation first, followed by the name of the anionanion
Writing Formulas from the Name of Writing Formulas from the Name of an Ionic Compoundan Ionic Compound
Compound name is lithium chlorideCompound name is lithium chloride LiLi++ and Cl and Cl-- are the ions are the ions Balance the chargesBalance the charges
Write the formulaWrite the formula LiClLiCl is the formula using the is the formula using the
subscripts from the charge balancesubscripts from the charge balance
0 )(1)(1
ClLi
11
Writing Formulas from the Name of Writing Formulas from the Name of an Ionic Compoundan Ionic Compound
Compound name is iron (III) oxideCompound name is iron (III) oxide FeFe3+3+ and O and O2-2- are the ions are the ions Balance the chargesBalance the charges
Write the formulaWrite the formula FeFe22OO33 is the formula using the is the formula using the
subscripts from the charge balancesubscripts from the charge balance
0 )(2)(3
OFe 23
2 3
Polyatomic IonsPolyatomic Ions Polyatomic ionsPolyatomic ions are a group of atoms are a group of atoms
covalently bonded together into a single unit covalently bonded together into a single unit The unit obtains a chargeThe unit obtains a charge Most PA ions are negatively charged Most PA ions are negatively charged
Oxyanions (anions): P, S, C, or N Oxyanions (anions): P, S, C, or N covalently bound to one or more oxygenscovalently bound to one or more oxygens
Never occur independently, always Never occur independently, always associated with ions of opposite chargeassociated with ions of opposite charge
Only one PA is positively chargedOnly one PA is positively charged ammonium ionammonium ion
Naming Ionic Compounds Containing a Naming Ionic Compounds Containing a Polyatomic IonPolyatomic Ion
Must Must memorizememorize name, formula and name, formula and charge (charge (Table 5.6 on page 138Table 5.6 on page 138). Look for ). Look for relationships between ionsrelationships between ions
Most PA ions areMost PA ions are oxyanions oxyanions: The number : The number of oxygen atoms bonded to the same of oxygen atoms bonded to the same element (e.g. P, S, or N) will determine element (e.g. P, S, or N) will determine the name (suffix) of the ionthe name (suffix) of the ion ~~ateate is most common is most common ~~iteite has one less oxygen bonded has one less oxygen bonded
Naming Ionic Compounds Containing a Naming Ionic Compounds Containing a Polyatomic IonPolyatomic Ion ~~ate, ate, ~~ite pairs of ionsite pairs of ions
The ion in the pair with the most oxygens is always the The ion in the pair with the most oxygens is always the ~~ate ionate ion
The ion in the pair with one less oxygen is always The ion in the pair with one less oxygen is always the the ~~ite ion ite ion
Ion pair with a 3- charge Ion pair with a 3- charge phosphphosphateate (PO (PO44
3-3-), phosph), phosphiteite (PO (PO333-3-))
Ion pair with a 2- charge Ion pair with a 2- charge sulfsulfateate (SO (SO44
2-2-), sulf), sulfiteite (SO (SO332-2-) )
Ion pair with a 1- chargeIon pair with a 1- charge nitrnitrateate (NO (NO33
--), nitr), nitriteite (NO (NO22--))
Naming Ionic Compounds Containing a Polyatomic IonNaming Ionic Compounds Containing a Polyatomic Ion
Group 7A elementsGroup 7A elements can form more than two can form more than two types of polyatomic ions (oxyanions)types of polyatomic ions (oxyanions)
Additional prefixes are used to differentiate Additional prefixes are used to differentiate the ionsthe ions
See page 138-9 (class text) and page 330 See page 138-9 (class text) and page 330 (lab text)(lab text)
The number of oxygens attached to the The number of oxygens attached to the central atom has an effect on the name of central atom has an effect on the name of the ionthe ion
e.g. Polyatomic ions of chlorine, bromine e.g. Polyatomic ions of chlorine, bromine and iodineand iodine
Naming Ionic Compounds Containing a Naming Ionic Compounds Containing a Polyatomic Ion (Group VIIA)Polyatomic Ion (Group VIIA)
Example: Polyatomic ions of chlorineExample: Polyatomic ions of chlorine
1)1) -ate ion-ate ion chlorchlorate ate = ClO= ClO33
--
2)2) -chlorate ion with 1 more O than -chlorate ion with 1 more O than chloratechlorate, use , use per-per- prefixprefix perperchlorate = ClOchlorate = ClO44
--
3)3) - - chloratechlorate ion with 1 less O, use ion with 1 less O, use -ite-ite suffix suffix chlorchloriteite = ClO = ClO22
--
4)4) --chloritechlorite ion with 1 less O, use ion with 1 less O, use hypo-hypo- prefix prefix hypohypochlorite = ClOchlorite = ClO--
Naming Ionic Compounds Containing a Naming Ionic Compounds Containing a Polyatomic IonPolyatomic Ion
Named the same way as binary ionic Named the same way as binary ionic compoundscompounds
Positive ion (metal) name is written firstPositive ion (metal) name is written first Polyatomic ions name follows the metalPolyatomic ions name follows the metal No prefixes are used in the nameNo prefixes are used in the name Cation: Check to see if metal is single or Cation: Check to see if metal is single or
multiple cationmultiple cation Use the name of the PA ion given in table Use the name of the PA ion given in table
5.6 on page 1385.6 on page 138
Naming Ionic Compounds Containing a Naming Ionic Compounds Containing a Polyatomic IonPolyatomic Ion
• CaSOCaSO44
• calcium sulfatecalcium sulfate• CaCa2+ 2+ and SOand SO44
2-2-
• LiLi22COCO33
• lithium carbonatelithium carbonate• LiLi++, CO, CO33
2-2-
• Al(NOAl(NO33))33
• aluminum nitratealuminum nitrate• AlAl3+3+, NO, NO33
--
Writing Formulas for Compounds Writing Formulas for Compounds Containing a Polyatomic IonContaining a Polyatomic Ion
Formulas are written like binary ionic Formulas are written like binary ionic compoundscompounds
Consider polyatomic ions as single units with Consider polyatomic ions as single units with a certain chargea certain charge
Obtain the correct ratio of cation to anion to Obtain the correct ratio of cation to anion to achieve a achieve a net charge of zeronet charge of zero
Use parentheses if more than one of the Use parentheses if more than one of the same PA unit is needed in a formulasame PA unit is needed in a formula
Use subscripts to indicate the number of a Use subscripts to indicate the number of a particular ion in a formulaparticular ion in a formula
Writing Formulas for Compounds Writing Formulas for Compounds Containing a Polyatomic IonContaining a Polyatomic Ion
Compound name is magnesium carbonateCompound name is magnesium carbonate MgMg2+2+ and CO and CO33
2-2- are the ions are the ions Balance the chargesBalance the charges
Write the formulaWrite the formula
MgCOMgCO33 is the formula using the is the formula using the
subscripts from the charge balancesubscripts from the charge balance
0 )(2)(2
COMg 23
2
1 1
Writing Formulas for Compounds Writing Formulas for Compounds Containing a Polyatomic IonContaining a Polyatomic Ion
Compound name is calcium nitrateCompound name is calcium nitrate CaCa2+2+ and NO and NO33
-- are the ions are the ions Balance the chargesBalance the charges
Write the formulaWrite the formula
Ca(NOCa(NO33))22 is the formula using the is the formula using the
subscripts from the charge balancesubscripts from the charge balance
0 )(1)(2
NOCa 32
1 2
Writing Formulas for Compounds Writing Formulas for Compounds Containing a Polyatomic IonContaining a Polyatomic Ion
Compound name is iron (III) sulfateCompound name is iron (III) sulfate FeFe3+3+ and SO and SO44
2-2- are the ions are the ions Balance the chargesBalance the charges
Write the formulaWrite the formula
FeFe22(SO(SO44))33 is the formula using the is the formula using the
subscripts from the charge balancesubscripts from the charge balance
0 )(2 )(3
SOFe 24
3
2 3
Writing Formulas for Compounds Writing Formulas for Compounds Containing a Polyatomic IonContaining a Polyatomic Ion
Compound name is ammonium phosphateCompound name is ammonium phosphate NHNH44
++ and PO and PO443-3- are the ions are the ions
Balance the chargesBalance the charges
Write the formulaWrite the formula
(NH(NH44))33POPO44 is the formula using the is the formula using the
subscripts from the charge balancesubscripts from the charge balance
0 )(3 )(1
PONH 34
4
3 1
Naming Molecular CompoundsNaming Molecular Compounds
Molecular binary compounds Molecular binary compounds Composed of two nonmetal elementsComposed of two nonmetal elements
Naming a compoundNaming a compound Use the full (element ) name for the first Use the full (element ) name for the first
nonmetalnonmetal Add the Add the –ide–ide ending to the full name of the ending to the full name of the
second nonmetalsecond nonmetal Second nonmetal named like the nonmetal in Second nonmetal named like the nonmetal in
binary ionic compounds (anion) binary ionic compounds (anion) Indicate the number of atoms by adding Indicate the number of atoms by adding
numerical prefixesnumerical prefixes
Prefixes Used in Naming Molecular (Covalent) Prefixes Used in Naming Molecular (Covalent) Compounds (page 140)Compounds (page 140)
SubscriptSubscript Prefix usedPrefix used
11 monomono~~ (Usually omitted on the first atom)(Usually omitted on the first atom)
22 di di ~~
33 tri tri ~~
44 tetra tetra ~~
55 penta penta ~~
66 hexa hexa ~~
77 hepta hepta ~~
88 octa octa ~~
99 nona nona ~~
1010 deca deca ~~
Naming Molecular CompoundsNaming Molecular Compounds
In ionic compounds the subscripts are not mentioned in In ionic compounds the subscripts are not mentioned in the namethe name
Many compounds can exist for many pairs of nonmetallic Many compounds can exist for many pairs of nonmetallic elements (e.g. nitrogen and oxygen)elements (e.g. nitrogen and oxygen)
ONNONO 22
BaCl2
barium chloride
barium dichloride
Na2SO4
sodium sulfate
disodium sulfate
nitrogen monoxide nitrogen dioxide dinitrogen monoxide
Prefix- Name of 1st nonmetal ___Prefix- Name of 2nd nonmetal + -ide
Naming Molecular CompoundsNaming Molecular Compounds IFIF55
iodine iodine pentapentafluorfluorideide
BB22OO33
didiboron boron tritrioxoxideide
NONO33
nitrogen nitrogen tritrioxoxideide
Naming Molecular CompoundsNaming Molecular Compounds
• AsClAsCl33• arsenic arsenic tritrichlorchlorideide
• COCO22
• carbon carbon didioxoxideide
• COCO• carbon carbon monmonoxoxideide
Naming Molecular (Covalent) Compounds Naming Molecular (Covalent) Compounds from their Chemical Formulafrom their Chemical Formula
When writing a formula from the When writing a formula from the namename of of a binary molecular compounda binary molecular compound
You must know (memorize) definition of You must know (memorize) definition of the numerical prefixes used in naming the numerical prefixes used in naming covalent compounds (see page 140) covalent compounds (see page 140)
1)1) Write the Write the symbolssymbols in order the in order the elements appear in the nameelements appear in the name
2)2) Identify the Identify the prefixesprefixes with the with the appropriate subscriptsappropriate subscripts
ExamplesExamples
• DiDinitrogen nitrogen PentPentoxideoxide• NN22OO55
• TetraTetraphosphorous phosphorous HexaHexasulfidesulfide• PP44NN66
• Iodine Iodine HeptaHeptasulfidesulfide• IFIF77
• MonoMonoiodine Heptasulfideiodine Heptasulfide
Naming Molecular Compounds A systematic name for a compound (IUPAC rules)
conveys information about the composition of the compound
Some compounds retain their “common” or “trivial” names which are not based upon IUPAC rules
These names were acquired before the systematic nomenclature was established
Naming Acids Naming Acids
Acids are hydrogen containing molecular Acids are hydrogen containing molecular compounds that produce Hcompounds that produce H+ + and an anion when and an anion when dissolved in waterdissolved in water
They have a sour taste and dissolve some They have a sour taste and dissolve some metalsmetals
They can be recognized by H written as the first They can be recognized by H written as the first element in their formulaselement in their formulas
Acids: HCl, H2S, H2SO4, HNO3
Nonacids: NH3, CH4, PH3, SiH4
Naming AcidsNaming Acids Many molecular compounds containing hydrogen Many molecular compounds containing hydrogen
dissolve in water to form Hdissolve in water to form H++ and an anion and an anion All acids produce HAll acids produce H++ ion which gives acids their ion which gives acids their
characteristic propertiescharacteristic properties The names of acids are derived from the names of The names of acids are derived from the names of
the anions produced by dissociation from the Hthe anions produced by dissociation from the H++ ion ion
Naming AcidsNaming Acids
Binary acidsBinary acids have a H have a H++ ion and a nonmetal ion and a nonmetal anionanion
OxyacidsOxyacids have a H have a H++ ion and a polyatomic ion and a polyatomic anion (PA ion contains oxygen)anion (PA ion contains oxygen)
There are three rules for naming acids There are three rules for naming acids depending on whether the name of the depending on whether the name of the anion has the suffixanion has the suffix - -ideide,-,-ateate, -, -iteite
Naming Binary Acids:Naming Binary Acids:
Anions Ending in -ideAnions Ending in -ide
Use the prefix Use the prefix hydro-hydro- before the base (root) before the base (root) name of the elementname of the element
Add the suffixAdd the suffix -ic-ic and the word and the word acidacid to the to the root name for the elementroot name for the element
Example: HClExample: HCl hydrohydrochlorchloricic acidacid
Example: HIExample: HI hydrohydroiodiodicic acidacid
Hydro- + base name of nonmetal + -ic______ acid
Naming OxyacidsNaming Oxyacids An oxyacid is a molecular compound composed An oxyacid is a molecular compound composed
of hydrogen, oxygen, and another nonmetalof hydrogen, oxygen, and another nonmetal Exist as pure compounds and water solutionsExist as pure compounds and water solutions Produce HProduce H++ and a polyatomic ion when and a polyatomic ion when
dissolved in waterdissolved in water
For many nonmetals there is a series of For many nonmetals there is a series of oxyacids and they differ only in the amount of oxyacids and they differ only in the amount of oxygen presentoxygen present
HClO4-, HClO3
-, HClO2-, HClO-
HNO3 H+ + NO3
-
SO42-, SO3
2- , NO3-, NO2
-
Naming OxyacidsNaming OxyacidsAnions Ending in -ateAnions Ending in -ate
A series of oxyanionsA series of oxyanions
Use the root name of the polyatomic ionUse the root name of the polyatomic ion If polyatomic ion ends in If polyatomic ion ends in –ate–ate, use , use –ic–ic suffix suffix
Example: HExample: H22SOSO44 (from SO (from SO442- 2- ,sulf,sulfateate ion) ion)
sulfursulfuric acid (NO hydro- prefix used)ic acid (NO hydro- prefix used)
base name of polyatomic ion + -ic______ acid
SO32-
sulfitesulfate
SO42-
Naming OxyacidsNaming OxyacidsAnions Ending in -iteAnions Ending in -ite
A series of oxyanionsA series of oxyanions
Use the root name of the polyatomic ionUse the root name of the polyatomic ion If polyatomic ion ends in If polyatomic ion ends in –ite–ite, use , use –ous–ous suffix suffix
Example: HExample: H22SOSO33 (from SO (from SO332- 2- ,sulf,sulfiteite ion) ion)
sulfursulfurous acid (NO hydro- prefix ous acid (NO hydro- prefix used)used)
base name of polyatomic ion + -ous______ acid
sulfate
SO42- SO3
2-
sulfite
Summary of Writing Ionic Summary of Writing Ionic CompoundsCompounds
Summary of guidelines when writing binary ionic Summary of guidelines when writing binary ionic compoundcompound
The symbol of the cation always precedes the The symbol of the cation always precedes the anionanion
The sum of the positive charges must equal the The sum of the positive charges must equal the sum of the negative charges:sum of the negative charges:A net charge of zeroA net charge of zero
Whole numbers are written as subscripts to Whole numbers are written as subscripts to indicate the number of each ion (or group) in the indicate the number of each ion (or group) in the formulaformula
Formula Mass: The Mass of a Molecule or Formula Unit
The formula mass is the sum of the atomic masses of atoms present in a single formula unit of a substance
It is obtained by adding the atomic masses of the constituent elements
Each atomic mass is counted as many times as the symbol occurs in the formulaCalculate the formula mass of Calcium NitrateChemical formula: Ca(NO3)2
Formula Mass = 1 (formula mass of Ca) + 2 (formula mass of N) + 6 (formula mass of O)
= 40.08 amu + 2 (14.01 amu) + 6 (16.00 amu) = 164.1 amu