Chapter 4 Compounds and Their Bonds

1

4.1 4.1 Valence Electrons Valence Electrons

4.2 4.2 Octet Rule and Ions Octet Rule and Ions

Chapter 4 Chapter 4 Compounds and Their BondsCompounds and Their Bonds

2

The The valence electronsvalence electrons are the are the electrons in the outer shell. electrons in the outer shell.

The electrons in the outer shell The electrons in the outer shell have the most contact with other have the most contact with other atoms and strongly influence the atoms and strongly influence the chemical properties of atoms. chemical properties of atoms.

Valence ElectronsValence Electrons

3

Number of Valence ElectronsNumber of Valence Electrons

For Group A elements, the number of For Group A elements, the number of valence electrons is the number of valence electrons is the number of electrons in the electrons in the ss and and pp subshells of the subshells of the outer shell.outer shell.

In the electron configuration for In the electron configuration for phosphorus, there are 5 valence phosphorus, there are 5 valence electrons in the electrons in the s s and and pp subshells with subshells with the highest number. the highest number.

5 valence electrons5 valence electrons

P P Group 5AGroup 5A 1 1ss2222ss2222pp6633ss2233pp33

4

Valence Electrons for GroupsValence Electrons for Groups

5

State the number of valence electrons State the number of valence electrons for each. for each.

A. MagnesiumA. Magnesium

1) 21) 2 2) 62) 6 3) 83) 8

B. OxygenB. Oxygen

1) 21) 2 2) 42) 4 3) 63) 6

C. PotassiumC. Potassium

1) 11) 1 2) 22) 2 3) 73) 7

Learning CheckLearning Check

6

State the number of valence electrons for State the number of valence electrons for each. each.

A. MagnesiumA. Magnesium

1) 2 1) 2 Group 2AGroup 2A 1 1ss2222ss2222pp6633ss2 2

B. OxygenB. Oxygen

3) 63) 6 Group 6AGroup 6A 1 1ss2222ss2 2 22pp4 4

C. PotassiumC. Potassium

1) 11) 1 Group 1AGroup 1A 1 1ss2222ss2222pp6633ss2233pp6644ss11

SolutionSolution

7

Electron Dot StructureElectron Dot Structure

An electron-dot An electron-dot structure is a structure is a convenient way to convenient way to represent the valence represent the valence electrons.electrons.

For example, the two For example, the two valence electrons for valence electrons for magnesium are placed magnesium are placed as single dots on any as single dots on any two sides of the Mg two sides of the Mg symbol.symbol.

8

Electron-Dot StructuresElectron-Dot Structures

Dot structures are used for Group A Dot structures are used for Group A elements.elements.

The valence electrons are placed on the sides The valence electrons are placed on the sides of the symbol of an element.of the symbol of an element.

9

A. X is the electron dot formula forA. X is the electron dot formula for

1) Na1) Na 2) K2) K 3) Al3) Al

B. B. X X is the electron dot formula is the electron dot formula

ofof

1) B1) B 2) N2) N 3) P 3) P


10

A. X is the electron dot formula forA. X is the electron dot formula for

1) Na1) Na 2) K2) K

B.B. XX iiss the electron dot formula the electron dot formula

ofof

2) N2) N 3) P 3) P

SolutionSolution

11

The stability of the noble gases is associated The stability of the noble gases is associated with with 8 valence electrons8 valence electrons (He has 2).(He has 2).

Ne Ne 2,2, 88ArAr 2, 8,2, 8, 88KrKr 2, 8, 18, 2, 8, 18, 88

Atoms can become more stable by acquiring Atoms can become more stable by acquiring an octet (8 electrons) in the outer shell. an octet (8 electrons) in the outer shell.

The process of acquiring an octet involves The process of acquiring an octet involves the the loss, gain, or sharingloss, gain, or sharing of valence of valence electrons.electrons.

Octet RuleOctet Rule

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Ionization EnergyIonization Energy

Ionization Ionization energyenergy is the is the energy it takes energy it takes to remove a to remove a valence valence electron.electron.

Metals have Metals have lower ionization lower ionization energies and energies and nonmetals have nonmetals have higher higher ionization ionization energies. energies.

13

Metals acquire octets by Metals acquire octets by losinglosing valencevalence electrons.electrons.

The loss of electrons converts an atom to The loss of electrons converts an atom to an an ionion that has the electron configuration that has the electron configuration of the nearest noble gas.of the nearest noble gas.

Metals form Metals form positivepositive ionsions because they because they have fewer electrons than protons.have fewer electrons than protons.

Group 1A metals Group 1A metals ion ion 1+1+



Metals Form Positive IonsMetals Form Positive Ions

14

Give the ionic charge for each ion. Give the ionic charge for each ion.

A. 12 pA. 12 p+ + and 10 e and 10 e--

1) 01) 0 2) 2+2) 2+ 3) 2-3) 2-

B. 50pB. 50p++ and 46 e and 46 e--

1) 2+1) 2+ 2) 4+2) 4+ 3) 4-3) 4-

C. 15 pC. 15 p++ and 18e and 18e--

2) 3+ 2) 3+ 2) 3-2) 3- 3) 3) 5- 5-


15

Give the ionic charge for each ion.Give the ionic charge for each ion.

A. 12 pA. 12 p+ + and 10 e and 10 e--

2) 2+2) 2+

B. 50pB. 50p++ and 46 e and 46 e--

2) 4+2) 4+

C. 15 pC. 15 p++ and 18e and 18e--

2) 3-2) 3-

SolutionSolution

16

Sodium forms an octet by losing its one Sodium forms an octet by losing its one valence electron.valence electron.Na Na – e – e Na Na ++

1s1s222s2s222p2p663s3s11 1s1s222s2s222p2p66 (= Ne)(= Ne)

A positive ion forms with a +1 charge.A positive ion forms with a +1 charge.Sodium atomSodium atom Sodium ionSodium ion 11 p11 p++ 11 p 11 p++

11 e11 e-- 10 e10 e--

00 1 1 ++

Formation of a Sodium Ion, Formation of a Sodium Ion, NaNa++

17

Magnesium forms an octet by losing its Magnesium forms an octet by losing its two valence electrons.two valence electrons. Magnesium atomMagnesium atom Magnesium ionMagnesium ion

Mg Mg – 2e – 2e MgMg2+2+

1s1s222s2s222p2p663s3s22 1s1s222s2s222p2p66 (= (= Ne)Ne)

A positive ion forms with a +2 charge.A positive ion forms with a +2 charge. 12 p12 p++ 12 p12 p++

12 e12 e- - 10 e10 e--

00 2 2 ++

Formation of MgFormation of Mg2+2+

18

When nonmetals When nonmetals gain electronsgain electrons to to achieve an octet arrangement, they achieve an octet arrangement, they form form negative ionsnegative ions. .

The ionic charge of a nonmetal is The ionic charge of a nonmetal is 3-, 2-, or 1-.3-, 2-, or 1-.

Formation of Negative IonsFormation of Negative Ions

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Fluorine forms an octet by adding an Fluorine forms an octet by adding an electron to its seven valence electrons.electron to its seven valence electrons.

11--

:: F F + e + e :: F F ::

1s1s222s2s222p2p55 1s1s222s2s222p2p66 (= Ne)(= Ne) A negative ion forms with a -1 charge.A negative ion forms with a -1 charge.

Fluorine atom Fluoride ionFluorine atom Fluoride ion 9 p9 p++ 9 p 9 p++

9 e9 e-- 10 e10 e--

00 1 1 ––

Formation of a Fluoride Ion, FFormation of a Fluoride Ion, F--

20

Group Number and IonsGroup Number and Ions

The The Group numberGroup number can be used to can be used to determine the charge of an ion.determine the charge of an ion.

The charge of a positive ion is The charge of a positive ion is equal to its Group number.equal to its Group number.

Group 3A = 3+Group 3A = 3+ The charge of a negative ion is The charge of a negative ion is

obtained by subtracting its Group obtained by subtracting its Group number from 8. number from 8.

Group 6A = - (8-6) = 2-Group 6A = - (8-6) = 2-

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Examples of Ionic ChargesExamples of Ionic Charges

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Some Important Ions in the Some Important Ions in the BodyBody

23

A.A. How many valence electrons does How many valence electrons does aluminum have?aluminum have?1) 2e1) 2e-- 2) 3e 2) 3e-- 3) 5e3) 5e--

B.B. How does aluminum acquire an octet? How does aluminum acquire an octet? 1) loses 3e1) loses 3e- - 2) gains 3e2) gains 3e- - 3) gains 3) gains

5e5e--

C. What is the ionic charge of an C. What is the ionic charge of an aluminum ion?aluminum ion?1) 3-1) 3- 2) 5- 2) 5- 3) 33) 3++

D. The symbol for the aluminum ion isD. The symbol for the aluminum ion is1) Al1) Al3+3+ 2) Al 2) Al3-3- 3) Al3) Al++


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A.A. How many valence electrons does How many valence electrons does aluminumaluminumhave?have?2) 3e2) 3e--

B.B. How does aluminum acquire an octet? How does aluminum acquire an octet? 1) loses 3e1) loses 3e- -

C. What is the ionic charge of an aluminum C. What is the ionic charge of an aluminum ion?ion?

3) 33) 3++ D. The symbol for the aluminum ion isD. The symbol for the aluminum ion is

1) Al1) Al3+3+

SolutionSolution

25


4.3 4.3 Ionic CompoundsIonic Compounds4.4 4.4 Naming and Writing Naming and Writing

Ionic FormulasIonic Formulas

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Ionic compounds consist of positive and Ionic compounds consist of positive and negative ions.negative ions.

An ionic bond is an attraction between An ionic bond is an attraction between the positive and negative charges. the positive and negative charges.

In an ionic formula, the total charge of In an ionic formula, the total charge of the positive ions is equal to the total the positive ions is equal to the total charge of the negative ions. charge of the negative ions.

total positive charge = total total positive charge = total negative chargenegative charge

Ionic CompoundsIonic Compounds

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The formulas of ionic compounds are The formulas of ionic compounds are determined from the charges on the ions.determined from the charges on the ions.

atomsatoms ions ions ––

Na Na + + F F :: Na Na+ + :: F F :: NaF NaF

sodium fluorine sodium sodium fluorine sodium fluoridefluoride

The overall charge of NaF is zero (0).The overall charge of NaF is zero (0).

((1+1+ ) + ( ) + (1-1-) = ) = 0 0

Ionic FormulasIonic Formulas

28

Charge Balance In NaClCharge Balance In NaCl

The formula does not show the charges of The formula does not show the charges of the ions in the compound.the ions in the compound.

The symbol of the metal is written first, The symbol of the metal is written first, followed by the symbol of the nonmetal.followed by the symbol of the nonmetal.

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Charge Balance In MgClCharge Balance In MgCl22

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Write the formula of the ionic compound Write the formula of the ionic compound that forms from Bathat forms from Ba2+2+ and Cl and Cl..

Write the symbols of the positive ion and Write the symbols of the positive ion and the negative ion. the negative ion. BaBa2+2+ Cl Cl

Balance the charges until the positive Balance the charges until the positive

charge is equal to the negative charge. charge is equal to the negative charge. BaBa2+2+ Cl Cl twotwo ClCl-- neededneeded

ClCl

Write the formula using subscripts for the Write the formula using subscripts for the number of ions for charge balance. number of ions for charge balance. BaClBaCl22

Writing a Formula from Writing a Formula from ChargesCharges

31

Write the correct formula for the ionic Write the correct formula for the ionic compound ofcompound of

A. NaA. Na+ + and and SS2-2-

1) NaS1) NaS 2) Na 2) Na22SS 3) NaS3) NaS22

B. AlB. Al3+ 3+ and Cland Cl--

1) AlCl1) AlCl33 2) AlCl 2) AlCl 3) Al3) Al33ClCl

C. MgC. Mg2+2+ and N and N3-3-

1) MgN1) MgN 2) Mg2) Mg22NN33 3) Mg3) Mg33NN22


32

A. A. NaNa+ + and and SS2-2-

2) Na2) Na22SS

B. AlB. Al3+ 3+ and Cland Cl--

1) AlCl1) AlCl33

C. MgC. Mg2+ 2+ and Nand N3-3-

3) Mg3) Mg33NN22

SolutionSolution

33

Names of IonsNames of Ions

Positive ions are named like the element.Positive ions are named like the element. Negative ions are named by changing the Negative ions are named by changing the

end of the element name to –end of the element name to –ide.ide.

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Complete the names of the following Complete the names of the following ions:ions:

NN33 O O22 F F

_________ _________ __________ __________ _________ _________

PP33 S S22 Cl Cl

_________ __________ __________________ __________ _________

Br Br

__________________


35

NN33 OO22 F F

nitridenitride oxideoxide fluoridefluoride

PP33 SS22 Cl Cl

phosphidephosphide sulfidesulfide chloridechloride

Br Br

bromidebromide

SolutionSolution

36

The name of a binary ionic The name of a binary ionic compound (two elements) gives the compound (two elements) gives the name of the metal ion first and the name of the metal ion first and the name of the negative ion second.name of the negative ion second.Examples: Examples: NaClNaCl sodium chloridesodium chlorideKK22SS potassium sulfidepotassium sulfideCaICaI22 calcium iodidecalcium iodideAlAl22OO33 aluminum oxidealuminum oxide

Naming Ionic Compounds with Naming Ionic Compounds with Two ElementsTwo Elements

37

Write the names of the following Write the names of the following compounds:compounds:

1) Na1) Na33NN ______________________

2) KBr2) KBr ______________________

3)3) Al Al22SS33 ___________ ___________

4) MgO4) MgO ______________________


38

Complete the names of the following Complete the names of the following compounds:compounds:

1)1) NaNa33NN sodium nitridesodium nitride

2)2) KBrKBr potassium bromidepotassium bromide

3)3) AlAl22SS33 aluminumaluminum sulfidesulfide

4)4) MgOMgO magnesium oxidemagnesium oxide

SolutionSolution

39

Most Most transitiotransition n elements elements have two have two or more or more positive positive ions.ions.

Ionic Charges of Transition Ionic Charges of Transition MetalsMetals

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Summary of Common IonsSummary of Common Ions

Of the transition metals, silver and zinc are Of the transition metals, silver and zinc are important elements that form only one ion.important elements that form only one ion.

41

A. The formula for the ionic A. The formula for the ionic compound of compound of

NaNa+ + and Oand O2-2- is is1) NaO1) NaO 2) Na2) Na22OO 3) NaO3) NaO22

B. The formula of a compound of B. The formula of a compound of aluminum and chlorine isaluminum and chlorine is1) Al1) Al33ClCl 2) AlCl2) AlCl22 3) AlCl3) AlCl33

C. The formula of FeC. The formula of Fe3+3+ and O and O2-2- is is 1) Fe1) Fe33OO22 2) FeO2) FeO33 3) Fe3) Fe22OO33


42

A. The formula for the ionic compound A. The formula for the ionic compound of of

NaNa+ + and Oand O2-2- is is2) Na2) Na22OO

B. The formula of a compound of B. The formula of a compound of aluminum and chlorine isaluminum and chlorine is

3) AlCl3) AlCl33

C. The formula of FeC. The formula of Fe3+3+ and O and O2-2- is is 3) Fe3) Fe22OO33

SolutionSolution

43

Naming Compounds with Naming Compounds with Transition MetalsTransition Metals

Transition metals with two different ions Transition metals with two different ions use a Roman numeral following the name use a Roman numeral following the name of the metal to indicate ionic charge.of the metal to indicate ionic charge.

44


Select the correct name for each.Select the correct name for each.A. FeA. Fe22SS33

1) iron sulfide1) iron sulfide 2) iron(II) sulfide2) iron(II) sulfide 3) iron (III) sulfide3) iron (III) sulfide

B. CuSOB. CuSO44

1) copper sulfate1) copper sulfate 2) copper(I) sulfate2) copper(I) sulfate 3) copper (II) sulfate3) copper (II) sulfate

45

SolutionSolution

Select the correct name for each.Select the correct name for each.A. FeA. Fe22SS33

3) iron (III) sulfide3) iron (III) sulfide

B. CuSOB. CuSO44

3) copper (II) sulfate3) copper (II) sulfate

46


The correct formula isThe correct formula is

A. Copper (I) nitrideA. Copper (I) nitride

1) CuN1) CuN 2) CuN2) CuN33 3) Cu 3) Cu33NN

B. Lead (IV) oxideB. Lead (IV) oxide

1) PbO1) PbO22 2) PbO2) PbO 3) Pb 3) Pb22OO44

47

SolutionSolution

The correct formula isThe correct formula is

A. Copper (I) nitrideA. Copper (I) nitride

3) Cu3) Cu33NN

B. Lead (IV) oxideB. Lead (IV) oxide

1) PbO1) PbO22

48

4.5 4.5 Covalent BondsCovalent Bonds

4.6 4.6 Naming and Writing Naming and Writing Formulas of Covalent Formulas of Covalent CompoundsCompounds

4.7 4.7 Bond PolarityBond Polarity


49

Covalent bonds form between Covalent bonds form between two nonmetals from Groups 4A, two nonmetals from Groups 4A, 5A, 6A, and 7A.5A, 6A, and 7A.

In a covalent bond, electrons are In a covalent bond, electrons are shared to complete octets.shared to complete octets.

Covalent BondsCovalent Bonds

50

Indicate whether a bond between Indicate whether a bond between the following is 1) Ionicthe following is 1) Ionic 2) 2) Covalent Covalent ____A.____A. sodium and oxygensodium and oxygen____B.____B. nitrogen and oxygennitrogen and oxygen

____C. ____C. phosphorus and chlorinephosphorus and chlorine

____D.____D. calcium and sulfurcalcium and sulfur

____E.____E. chlorine and brominechlorine and bromine


51

Indicate whether a bond between Indicate whether a bond between the following is 1) Ionicthe following is 1) Ionic 2) 2) Covalent Covalent

1 1 A. A. sodium and oxygensodium and oxygen

2 2 B. B. nitrogen and oxygennitrogen and oxygen

2 2 C. C. phosphorus and chlorinephosphorus and chlorine

1 1 D. D. calcium and sulfurcalcium and sulfur

2 2 E. E. chlorine and brominechlorine and bromine

SolutionSolution

52

In hydrogen, two hydrogen atoms share In hydrogen, two hydrogen atoms share their electrons to form a covalent bond.their electrons to form a covalent bond.

Each hydrogen atom acquires a stable Each hydrogen atom acquires a stable outer shell of two (2) electrons like outer shell of two (2) electrons like helium (He).helium (He).

HH ++ H H H : H = H H : H = HH = HH = H22

hydrogen moleculehydrogen molecule

HH22, A Covalent Molecule, A Covalent Molecule

53

Diatomic ElementsDiatomic Elements

As As elements, elements, the the following following share share electrons to electrons to form form diatomic, diatomic, covalent covalent molecules.molecules.

54

What is the name of each of the What is the name of each of the following diatomic molecules?following diatomic molecules?

HH22 hydrogenhydrogen

NN22 nitrogennitrogen

ClCl22 ______________________________

OO22 ______________________________

II22 ______________________________


55

What are the names of each of the What are the names of each of the following diatomic molecules?following diatomic molecules?

HH22 hydrogenhydrogen

NN22 nitrogennitrogen

ClCl22 chlorine chlorine

OO22 oxygenoxygen

II22 iodineiodine

SolutionSolution

56

The compound NHThe compound NH33 consists of a N atom consists of a N atom and three H atoms.and three H atoms.

NN and 3 and 3 HH

By sharing electrons to form NHBy sharing electrons to form NH33, the , the electron dot structure is written aselectron dot structure is written as

HH Bonding pairsBonding pairs

H H :: N N :: H H Lone pair of electronsLone pair of electrons

Covalent Bonds in NHCovalent Bonds in NH33

57

Number of Covalent BondsNumber of Covalent Bonds

Often, the number of covalent bonds Often, the number of covalent bonds formed by a nonmetal is equal to the formed by a nonmetal is equal to the number of electrons needed to number of electrons needed to complete the octet.complete the octet.

58

Dot Structures and Models of Dot Structures and Models of Some Covalent CompoundsSome Covalent Compounds

59

Multiple BondsMultiple Bonds

Sharing one pair of electrons is a Sharing one pair of electrons is a single bond.single bond.

X X :: X or X X or X–X–X In multiple bonds, two pairs of In multiple bonds, two pairs of

electrons are shared to form a electrons are shared to form a double double bond bond or three pairs of electrons are or three pairs of electrons are shared in a shared in a triple bond.triple bond.

X X : :: : X or X X or X =X=X

X X :: :: :: X or X X or X ≡≡ XX

60

In nitrogen, octets are achieved by In nitrogen, octets are achieved by sharing three pairs of electrons.sharing three pairs of electrons.

When three pairs of electrons are When three pairs of electrons are shared, the multiple bond is called a shared, the multiple bond is called a triple bond.triple bond.

octetsoctets N N + +

N N N:::N N:::N

triple bondtriple bond

Multiple Bonds in NMultiple Bonds in N22

61

In the name of a In the name of a covalent covalent compound, the compound, the first nonmetal is first nonmetal is named followed by named followed by the name of the the name of the second nonmetal second nonmetal ending in –ide.ending in –ide.

Prefixes indicate Prefixes indicate the number of the number of atoms of each atoms of each element.element.

Naming Covalent CompoundsNaming Covalent Compounds

62

Complete the name of each covalent Complete the name of each covalent

compound:compound:

COCO carbon ______oxidecarbon ______oxide

COCO22 carbon _______________carbon _______________

PClPCl33 phosphorus ___________phosphorus ___________

CClCCl44 carbon _______________carbon _______________

NN22OO ____________________________________________


63

Complete the name of each covalent Complete the name of each covalent

compound:compound:

CO CO carbon carbon monmonoxideoxide

COCO22 carbon carbon dioxidedioxide

PClPCl33 phosphorus phosphorus trichloridetrichloride

CClCCl44 carbon carbon tetrachloridetetrachloride

NN22OO dinitrogen monoxidedinitrogen monoxide

SolutionSolution

64

Formulas and Names of Some Formulas and Names of Some Covalent CompoundsCovalent Compounds

65

Select the correct name for each Select the correct name for each compound.compound.

A.A. SiClSiCl44 1) silicon chloride1) silicon chloride2) tetrasilicon chloride2) tetrasilicon chloride3) silicon tetrachloride3) silicon tetrachloride

B. B. PP22OO55 1) phosphorus oxide1) phosphorus oxide2) phosphorus pentoxide2) phosphorus pentoxide3) diphosphorus pentoxide3) diphosphorus pentoxide

C.C. ClCl22OO77 1) dichlorine heptoxide1) dichlorine heptoxide2) dichlorine oxide2) dichlorine oxide3) chlorine heptoxide 3) chlorine heptoxide


66

Select the correct name for each Select the correct name for each compound.compound.

A.A. SiClSiCl44 3) silicon tetrachloride3) silicon tetrachloride

B. B. PP22OO55 3) diphosphorus pentoxide3) diphosphorus pentoxide

C.C. ClCl22OO77 1) dichlorine heptoxide1) dichlorine heptoxide

SolutionSolution

67

Electronegativity is the attraction Electronegativity is the attraction of an atom for shared electrons. of an atom for shared electrons.

The nonmetals have high The nonmetals have high electronegativity values with electronegativity values with fluorine as the highest. fluorine as the highest.

The metals have low The metals have low electronegativity values.electronegativity values.

ElectronegativityElectronegativity

68

Some Electronegativity Values Some Electronegativity Values for Group A Elementsfor Group A Elements

69

The atoms in a The atoms in a nonpolar covalent bond nonpolar covalent bond have electronegativity differences of 0.3 have electronegativity differences of 0.3 or less.or less.

Examples: Examples: Atoms Atoms ElectronegativityElectronegativity Type of Type of

DifferenceDifference Bond Bond N-NN-N 3.0 - 3.0 = 0.03.0 - 3.0 = 0.0 Nonpolar Nonpolar covalentcovalentCl-BrCl-Br 3.0 - 2.8 = 0.23.0 - 2.8 = 0.2 Nonpolar Nonpolar covalentcovalentH-SiH-Si2.1 - 1.8 = 0.32.1 - 1.8 = 0.3 Nonpolar covalent Nonpolar covalent

Nonpolar Covalent BondsNonpolar Covalent Bonds

70

The atoms in a The atoms in a polar covalent bond polar covalent bond have have electronegativity differences of 0.4 to 1.6.electronegativity differences of 0.4 to 1.6.

Examples: Examples: Atoms Atoms ElectronegativityElectronegativity Type of Type of

DifferenceDifference Bond BondO-ClO-Cl 3.5 - 3.0 = 0.53.5 - 3.0 = 0.5 Polar covalent Polar covalentCl-CCl-C 3.0 - 2.5 = 0.53.0 - 2.5 = 0.5 Polar covalent Polar covalentO-S O-S 3.5 - 2.5= 1.03.5 - 2.5= 1.0 Polar covalent Polar covalent

Polar Covalent BondsPolar Covalent Bonds

71

Comparing Nonpolar and Comparing Nonpolar and Polar Covalent BondsPolar Covalent Bonds

72

Ionic BondsIonic Bonds

The atoms in an The atoms in an ionic bond ionic bond have have electronegativity differences of 1.7 or electronegativity differences of 1.7 or more.more.

Examples: Examples: Atoms Atoms ElectronegativityElectronegativity Type Type ofof DifferenceDifference BondBondCl-KCl-K 3.0 – 0.8 3.0 – 0.8 = 2.2= 2.2 IonicIonicN-NaN-Na 3.0 – 0.9 3.0 – 0.9 = 2.1= 2.1 IonicIonicS-CsS-Cs2.5 – 0.72.5 – 0.7 = 1.8= 1.8 Ionic Ionic

73

Range of Bond TypesRange of Bond Types

74

Predicting Bond TypePredicting Bond Type

75

Identify the type of bond between Identify the type of bond between the following asthe following as

1) nonpolar covalent 1) nonpolar covalent

2) polar covalent 2) polar covalent

3) ionic3) ionic A. K-NA. K-N

B. N-OB. N-O

C. Cl-ClC. Cl-Cl


76

A. K-NA. K-N3) ionic3) ionic

B. N-OB. N-O2) polar covalent2) polar covalent

C. Cl-ClC. Cl-Cl1) nonpolar covalent 1) nonpolar covalent

SolutionSolution

77

4.8 Polyatomic Ions4.8 Polyatomic Ions


78

A polyatomic ion is a group of two or more A polyatomic ion is a group of two or more atoms that has an overall ionic charge.atoms that has an overall ionic charge.

Some examples of polyatomic ions areSome examples of polyatomic ions are

NHNH44++ ammoniumammonium OHOH - - hydroxide hydroxide

NONO33-- nitratenitrate NONO2 2

-- nitrite nitrite

COCO332 -2 - carbonatecarbonate POPO44

3 - 3 - phosphatephosphate

HCOHCO33 - - hydrogen carbonate (bicarbonate)hydrogen carbonate (bicarbonate)

Polyatomic IonsPolyatomic Ions

79

Common Polyatomic IonsCommon Polyatomic Ions

80

Formulas with Polyatomic IonsFormulas with Polyatomic Ions

The formula of an ionic compound The formula of an ionic compound containing a polyatomic ion is written to containing a polyatomic ion is written to make the overall charge equal zero (0).make the overall charge equal zero (0).NaNa++ and NO and NO33

- - NaNONaNO33

When two or more polyatomic ions are When two or more polyatomic ions are needed, the polyatomic ion is enclosed in needed, the polyatomic ion is enclosed in parentheses.parentheses.polyatomic ionpolyatomic ion

MgMg2+2+ and NO and NO3 3 - - MgMg(NO(NO33))22

subscript 2 for charge balancesubscript 2 for charge balance

81

Some Compounds with Some Compounds with Polyatomic IonsPolyatomic Ions

82

Select the correct formula for each:Select the correct formula for each:A. Aluminum nitrate A. Aluminum nitrate 1) AlNO1) AlNO3 3 2) Al(NO)2) Al(NO)33 3) Al(NO3) Al(NO33))33

B. Copper(II) nitrateB. Copper(II) nitrate 1) CuNO1) CuNO33 2) Cu(NO2) Cu(NO33))22 3) Cu3) Cu22(NO(NO33))

C. Iron (III) hydroxideC. Iron (III) hydroxide 1) FeOH1) FeOH 2) Fe2) Fe33OHOH 3) Fe(OH)3) Fe(OH)33

D. Tin(IV) hydroxideD. Tin(IV) hydroxide 1) Sn(OH)1) Sn(OH)44 2) Sn(OH)2) Sn(OH)22 3) 3) SnSn44(OH)(OH)


83

Select the correct formula for each:Select the correct formula for each:A. A. Aluminum nitrate Aluminum nitrate 3) Al(NO3) Al(NO33))33

B. B. Copper(II) nitrateCopper(II) nitrate 2) Cu(NO2) Cu(NO33))22

C. C. Iron (III) hydroxideIron (III) hydroxide 3) Fe(OH)3) Fe(OH)33

D. D. Tin(IV) hydroxideTin(IV) hydroxide 1) Sn(OH)1) Sn(OH)44

SolutionSolution

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For compounds with polyatomic ions, For compounds with polyatomic ions, the positive ion is named first the positive ion is named first followed by the name of the followed by the name of the polyatomic ion.polyatomic ion.NaNaNONO33 sodium sodium nitratenitrateKK22SOSO44 potassium potassium sulfatesulfateAlAl(HCO(HCO33))33 aluminumaluminum bicarbonatebicarbonate

oror aluminumaluminum hydrogen hydrogen carbonatecarbonate(NH(NH44))33POPO44 ammonium phosphateammonium phosphate

Naming Compounds with Naming Compounds with Polyatomic IonsPolyatomic Ions

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Match each formula with the correct Match each formula with the correct name:name:

A.A. NaNa22COCO33 1) magnesium sulfite 1) magnesium sulfite

MgSOMgSO33 2) magnesium sulfate2) magnesium sulfate

MgSOMgSO44 3) sodium carbonate 3) sodium carbonate

B.B. Ca(HCO Ca(HCO33))22 1) calcium carbonate1) calcium carbonate

CaCOCaCO33 2) calcium phosphate2) calcium phosphate

CaCa33(PO(PO44))2 2 3) calcium bicarbonate3) calcium bicarbonate


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A.A. NaNa22COCO33 3) sodium carbonate 3) sodium carbonate

MgSOMgSO33 1) magnesium sulfite1) magnesium sulfite

MgSOMgSO44 2) magnesium sulfate2) magnesium sulfate

B.B. Ca(HCO Ca(HCO33))22 3) calcium 3) calcium bicarbonatebicarbonate CaCOCaCO33 1) calcium carbonate1) calcium carbonate

CaCa33(PO(PO44))2 2 2) calcium phosphate2) calcium phosphate

SolutionSolution

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Summary of Naming Summary of Naming CompoundsCompounds

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Naming RulesNaming Rules

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Naming Rules (continued)Naming Rules (continued)

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Name each of the following compounds:Name each of the following compounds:

A.A. Mg(NOMg(NO33))22

B.B. CuClCuCl22

C.C. NN22OO44

D.D. FeFe22(SO(SO44))33

E.E. BaBa33(PO(PO44))22

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SolutionSolution

Name each of the following compounds:Name each of the following compounds:

A.A. Mg(NOMg(NO33))22 magnesium nitratemagnesium nitrate

B.B. CuClCuCl22 copper(II) chloridecopper(II) chloride

C.C. NN22OO44 dinitrogen tetroxidedinitrogen tetroxide

D.D. FeFe22(SO(SO44))33iron(III) sulfateiron(III) sulfate

E.E. BaBa33(PO(PO44))22 barium phosphatebarium phosphate

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Write the correct formula for each:Write the correct formula for each:

A.A. potassium sulfidepotassium sulfide

B.B. calcium carbonatecalcium carbonate

C.C. sodium phosphitesodium phosphite

D.D. iron(III) oxideiron(III) oxide

E.E. iron (II) nitrateiron (II) nitrate

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SolutionSolution

Write the correct formula for each:Write the correct formula for each:

A.A. potassium sulfidepotassium sulfide KK22SS

B.B. calcium carbonatecalcium carbonate CaCOCaCO33

C.C. sodium phosphitesodium phosphite NaNa33POPO33

D.D. iron(III) oxideiron(III) oxide FeFe22OO33

E.E. iron (II) nitrateiron (II) nitrate Fe(NOFe(NO33))22

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4.9 4.9 Shapes of Molecules Shapes of Molecules

4.104.10 Polar and Nonpolar Polar and Nonpolar MoleculesMolecules

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VSEPRVSEPR

The shape of a molecule is predicted The shape of a molecule is predicted from the geometry of the electrons from the geometry of the electrons pairs around the central atom.pairs around the central atom.

In the In the valence-shell electron-pair valence-shell electron-pair repulsion theory (VSEPR),repulsion theory (VSEPR), the the electron pairs are arranged as far electron pairs are arranged as far apart as possible to give the least apart as possible to give the least amount of repulsion of the negatively amount of repulsion of the negatively charged electrons.charged electrons.

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Two Electron PairsTwo Electron Pairs

In a molecule of BeClIn a molecule of BeCl22, there are two , there are two bonding pairs around the central bonding pairs around the central atom Be. (Be is an exception to the atom Be. (Be is an exception to the octet rule.)octet rule.)

The arrangement of two electron pairs The arrangement of two electron pairs to minimize their repulsion is 180to minimize their repulsion is 180° ° or opposite each other.or opposite each other.

The shape of the molecule is The shape of the molecule is linear.linear.

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Two Electron Pairs with Two Electron Pairs with Double BondsDouble Bonds

The electron-dot structure for COThe electron-dot structure for CO2 2 consists of two double bonds to the consists of two double bonds to the central atom C. central atom C.

Because the electrons in a double bond Because the electrons in a double bond are held together, a double bond is are held together, a double bond is counted as a single unit.counted as a single unit.

Repulsion is minimized when the double Repulsion is minimized when the double bonds are placed opposite each other at bonds are placed opposite each other at 180180° to give a ° to give a linear shape.linear shape.

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Three Electron PairsThree Electron Pairs

In BFIn BF33, there are 3 electron pairs around , there are 3 electron pairs around the central atom B. (B is an exception to the the central atom B. (B is an exception to the octet rule.)octet rule.)

Repulsion is minimized by placing three Repulsion is minimized by placing three electron pairs in a plane at angles of 120electron pairs in a plane at angles of 120°, °, which is a which is a trigonal planar trigonal planar arrangement.arrangement.

The shape with three bonded atoms is The shape with three bonded atoms is trigonal planartrigonal planar..

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Two Bonding Pairs and A Two Bonding Pairs and A Nonbonding PairNonbonding Pair

In SOIn SO22, there are 3 electron units around , there are 3 electron units around the central atom S. the central atom S.

Two electron units are bonded to atoms Two electron units are bonded to atoms and one electron pair is a nonbonding and one electron pair is a nonbonding pair.pair.

Repulsion is minimized by placing three Repulsion is minimized by placing three electron pairs in a plane at angles of 120electron pairs in a plane at angles of 120°, °, which is which is trigonal planar.trigonal planar.

The shape with two bonded atoms is The shape with two bonded atoms is bent.bent.

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The shape of a molecule of NThe shape of a molecule of N22O (N N O) O (N N O) isis

1) linear1) linear

2) trigonal planar2) trigonal planar

3) bent (1203) bent (120°)°)

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SolutionSolution

The shape of a molecule of NThe shape of a molecule of N22O (N N O) isO (N N O) is1) linear1) linear

The electron-dot structure uses 5 e for The electron-dot structure uses 5 e for each N and 6 e for O (16 e total) has each N and 6 e for O (16 e total) has octets using two double bond to the octets using two double bond to the central N and one nonbonding pair. The central N and one nonbonding pair. The shape with two bonded atoms is linearshape with two bonded atoms is linear..

• • • •• • • •

:: N N :::: N N :::: O O ::

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Four Electron PairsFour Electron Pairs

In CHIn CH44, there are 4 electron pairs , there are 4 electron pairs around the central atom C. around the central atom C.

Repulsion is minimized by placing Repulsion is minimized by placing four electron pairs at angles of 109four electron pairs at angles of 109°, °, which is a which is a tetrahedral tetrahedral arrangement.arrangement.

The shape with four bonded atoms is The shape with four bonded atoms is called called tetrahedraltetrahedral..

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Three Bonding Atoms and One Three Bonding Atoms and One Nonbonding PairNonbonding Pair

In NHIn NH33, there are 4 electron pairs around the , there are 4 electron pairs around the N. N.

Three pairs are bonded to atoms and one is a Three pairs are bonded to atoms and one is a nonbonding pair.nonbonding pair.

Repulsion is minimized by placing four Repulsion is minimized by placing four electron pairs at angles of 109electron pairs at angles of 109°, which is a °, which is a tetrahedral tetrahedral arrangement.arrangement.

The shape with three bonded atoms is The shape with three bonded atoms is pyramidalpyramidal..

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Two Bonding Atoms and Two Two Bonding Atoms and Two Lone PairsLone Pairs

In HIn H22O, there are 4 electron pairs O, there are 4 electron pairs around O. around O.

Two pairs are bonded to atoms and two Two pairs are bonded to atoms and two are nonbonding pairs.are nonbonding pairs.

Repulsion is minimized by placing four Repulsion is minimized by placing four electron pairs at angles of 109electron pairs at angles of 109° called ° called a a tetrahedral tetrahedral arrangement.arrangement.

The shape with two bonded atoms is The shape with two bonded atoms is called called bentbent..

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Some Steps Using VSEPR to Some Steps Using VSEPR to Predict ShapePredict Shape

Draw the electron dot structure.Draw the electron dot structure. Count the electron pairs around the Count the electron pairs around the

central atom.central atom. Arrange the electron pairs to Arrange the electron pairs to

minimize repulsion.minimize repulsion. Determine the shape using the Determine the shape using the

number of bonded atoms in the number of bonded atoms in the electron arrangement. electron arrangement.

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Summary of Electron Summary of Electron Arrangements and ShapesArrangements and Shapes

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Use VSEPR theory to determine the Use VSEPR theory to determine the shape of the following molecules or shape of the following molecules or ions.ions.

1) tetrahedral 1) tetrahedral 2) pyramidal 2) pyramidal3) bent3) bent

A. PFA. PF33

B. HB. H22SS

C. CClC. CCl44

D. POD. PO443-3-

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SolutionSolution

Use VSEPR theory to determine the Use VSEPR theory to determine the shape of the following molecules or shape of the following molecules or ions.ions.

1) tetrahedral1) tetrahedral 2) pyramidal2) pyramidal 3) 3) bentbent

A. A. PFPF33 2) pyramidal2) pyramidal

B.B. HH22SS 3) bent3) bent

C. C. CClCCl44 1) tetrahedral1) tetrahedral

D. D. POPO443-3- 1) tetrahedral1) tetrahedral

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Polar MoleculesPolar Molecules

A A polar molecule polar molecule contains polar contains polar bonds.bonds.

The separation of positive and The separation of positive and negative charge is called a dipole.negative charge is called a dipole.

In a polar molecule, dipoles do not In a polar molecule, dipoles do not cancel.cancel.

++ -- • •• •

HH–Cl–Cl Cl–N–Cl Cl–N–Cl dipoledipole ClCl

dipoles do not canceldipoles do not cancel

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Nonpolar MoleculesNonpolar Molecules

A A nonpolar moleculenonpolar molecule contains nonpolar contains nonpolar bondsbonds

ClCl–Cl–Cl H–HH–H

or a symmetrical arrangement of polar or a symmetrical arrangement of polar bonds.bonds.

O=C=OO=C=O ClCl

Cl–C–Cl Cl–C–Cl ClCl

dipoles canceldipoles cancel

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Identify each of the following molecules Identify each of the following molecules as as

1) polar or 2) nonpolar. Explain.1) polar or 2) nonpolar. Explain.

A. PBrA. PBr33

B. HBrB. HBr

C. BrC. Br22

D. SiBrD. SiBr44

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SolutionSolution

Identify each of the following molecules Identify each of the following molecules as as

1) polar or 2) nonpolar. Explain.1) polar or 2) nonpolar. Explain.

A. PBrA. PBr33 1) polar; pyramidal1) polar; pyramidal

B. HBrB. HBr 1) polar; polar bond1) polar; polar bond

C. BrC. Br22 2) nonpolar, nonpolar bond2) nonpolar, nonpolar bond

D. SiBrD. SiBr44 2) nonpolar; dipoles cancel2) nonpolar; dipoles cancel

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Chapter 4 Compounds and Their Bonds