1 CH110 Chapter 4: Compounds & Bonds Valence Electrons & e – Dot Structures Octet Rule & Ions Ionic Compounds Covalent Compounds Molecular Shapes & Polarity.

1

CH110CH110Chapter 4: Compounds & BondsChapter 4: Compounds & Bonds

Valence Electrons & eValence Electrons & e–– Dot Structures Dot Structures

Octet RuleOctet Rule & & IonsIons

Ionic CompoundsIonic Compounds

Covalent CompoundsCovalent Compounds

Molecular Shapes & Molecular Shapes & PolarityPolarity

2

Electron arrangementElectron arrangement

2288

18183232

Electronsfill layers

around nucleusLow High

Electronsfill layers

around nucleusLow High

Shells = Energy levelsShells = Energy levels

2424

1212MgMg

A new layer isadded for each row or period in the table.

A new layer isadded for each row or period in the table.

2n2

3

11

11HH

77

33LiLi

44

22HeHe

99

44BeBe 2020

1010NeNe

2323

1111NaNa

2424

1212MgMg4040

1818ArAr

88881111

2222

2, 12, 12, 12, 1 2, 22, 22, 22, 2 2, 82, 82, 82, 8

2, 8, 12, 8, 12, 8, 12, 8, 1 2, 8, 22, 8, 22, 8, 22, 8, 2 2, 8, 82, 8, 82, 8, 82, 8, 8

Octet RuleOctet Rule

4

11

11HH

77

33LiLi

2323

1111NaNa

Lewis StructuresLewis Structures

Show only Valence

Electrons

H

Li

Na

K

5

H

Li

Na

K

He

Be B C O F NeN

Mg

Ca

Al

Ga

Si

Ge

P

As

S

Se

Cl

Br

Ar

Kr

1

2 3 4 5 6 7

8

6

2323

1111NaNaIonsIons

Metals give eMetals give e--s to make s to make Cations (+)Cations (+)

Na11 +’s11 +’s

11 -’s11 -’s

00

11 +’s11 +’s

11 -’s11 -’s

00

11 +’s11 +’s

10 -’s10 -’s

1 +1 +

11 +’s11 +’s

10 -’s10 -’s

1 +1 +

NaNa1+1+oror Na Na++

2, 8 = [Ne]2, 8 = [Ne]2, 8 = [Ne]2, 8 = [Ne]

2, 8, 1 2, 8, 1 2, 8, 1 2, 8, 1

7

IonsIons

Nonmetals take eNonmetals take e--s to make s to make Anions (–)Anions (–)

17 +’s17 +’s

17 -’s17 -’s

00

17 +’s17 +’s

17 -’s17 -’s

00

17 +’s17 +’s

18 -’s18 -’s

1 -1 -

17 +’s17 +’s

18 -’s18 -’s

1 -1 -

Cl

Cl1-1-

3535

1717ClCl

= Cl= Cl1– 1–

2, 8, 8 = [Ar]2, 8, 8 = [Ar]2, 8, 8 = [Ar]2, 8, 8 = [Ar]

2, 8, 72, 8, 72, 8, 72, 8, 7

ClCl––

8

Formation of NaClFormation of NaCl

Na + Cl Na+ + Cl

+ and - ions attract to form an ionic bond.

_

e– moves from Metal Nonmetal

Metal Cation

Nonmetal Anion

Stable octets

9

Ionic compoundsIonic compounds

• Not individual molecules• Form crystal arrays• Ions touch many others • Formula represents the average ion ratio

NaNaClClsodiumsodium chloridechloride

NaNaClClsodiumsodium chloridechloride

Na

NaNa

Cl

Cl Cl

10

Common ionsCommon ions

H

Li

Na

Cs

Rb

K

TlHgAuHfLsBa

Fr

PtIrOsReWTa

He

RnAtPoBiPb

Be

Mg

Sr

Ca

CdAgZrY PdRhRuTcMoNb

AcRa

ZnCuTiSc NiCoFeMnCrV

In XeITeSbSn

Ga KrBrSeAsGe

Al ArClSPSi

B NeFONC

Gd

Cm

Tb

Bk

Sm

Pu

Eu

Am

Nd

U

Pm

Np

Ce

Th

Pr

Pa

Yb

No

Lu

Lr

Er

Fm

Tm

Md

Dy

Cf

Ho

Es4 - 6

1+1+1+1+

2+2+2+2+ 3+3+3+3+

4+4+

4-4-

4+4+

4-4- 3-3-3-3- 2-2-2-2- 1-1-1-1-

Representative ElementsRepresentative ElementsRepresentative ElementsRepresentative Elements

11

Ionic FormulasIonic FormulasMetal Cations Metal Cations ++ NonmetalNonmetal AnionsAnions

NaNa1+1+ ClCl1- 1-

NaNaClClSodiumSodium ChlorChlorideide

AlAl3+3+ ClCl1- 1-

AlAlClCl33Aluminum Aluminum ChlorChlorideide

ClCl1- 1-

ClCl1- 1-

12

Common ionsCommon ions

H

Li

Na

Cs

Rb

K

TlBa

Fr

He

RnAtPoBiPb

Be

Mg

Sr

Ca

Ra

In XeITeSbSn

Ga KrBrSeAsGe

Al ArClSPSi

B NeFONC

HgAuHfLs PtIrOsReWTa

CdAgZrY PdRhRuTcMoNb

Ac

ZnCuTiSc NiCoFeMnCrV

Gd

Cm

Tb

Bk

Sm

Pu

Eu

Am

Nd

U

Pm

Np

Ce

Th

Pr

Pa

Yb

No

Lu

Lr

Er

Fm

Tm

Md

Dy

Cf

Ho

Es

1+1+1+1+

2+2+2+2+ 3+3+3+3+

4+4+

4-4-

4+4+

4-4- 3-3-3-3- 2-2-2-2- 1-1-1-1-

Transition ElementsTransition ElementsTransition ElementsTransition Elements

VariableVariableVariableVariable

Representative ElementsRepresentative ElementsRepresentative ElementsRepresentative Elements

13

14

Information in the tableInformation in the table

Fe

55.845

Elemental Symbol

Electronic Configuration

Atomic mass (weight)26

Iron

2,3

[Ar]3d64s2

Atomic number

Name of the element

Possible ChargesPossible Charges (Valence)(Valence) Possible ChargesPossible Charges (Valence)(Valence)

No longer discussed in text

15

16

Transition Metal IonsTransition Metal Ions

FeFe2+2+ ClCl1- 1-

FeFeClCl22

Iron(II)Iron(II) ChlorChlorideide

FeFe3+3+ ClCl1- 1-

FeFeClCl33

Iron(III) Iron(III) ChlorChlorideide

ClCl1- 1-

ClCl1- 1- ClCl1- 1-

FerrousFerrous ChlorChlorideide Ferric Ferric ChlorChlorideide

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Polyatomic IonsPolyatomic Ions

NaNa1+1+ SOSO442- 2-

NaNa22SOSO44

SodiumSodium SulfSulfateate

NHNH441+1+ POPO44

3- 3-

(NH(NH44))33POPO44

Ammonium Ammonium PhosphPhosphateate

NHNH441+1+

NHNH441+1+

NaNa1+1+

18

Names and Formulas of Common Names and Formulas of Common Polyatomic IonsPolyatomic Ions

19

Ionic compoundsIonic compounds

NaNa++

MgMg2+2+

AlAl3+3+

ClCl-- OO2-2- NN3-3-

Some simple ionsSome simple ions

NaClNaCl

Anions

Cat

ion

s

NaNa22OO NaNa33NN

MgClMgCl22

AlClAlCl33

MgOMgO

AlAl22OO33

MgMg33NN22

AlNAlN

20

Ionic compoundsIonic compoundsC

atio

ns

Anions

NaNa1+1+

MgMg2+2+

AlAl3+3+

BrBr1-1- OO2-2- NN3-3-

NaBrNaBr NaNa22OO NaNa33NN

MgBrMgBr22

AlBrAlBr33

MgOMgO

AlAl22OO33

MgMg33NN22

AlNAlN

FeFe3+3+

CuCu1+1+

FeBrFeBr33 FeFe22OO33FeNFeN

CuBrCuBr CuCu22OO CuCu33NN

Sodium BromideSodium Bromide Sodium OxideSodium Oxide Sodium NitrideSodium Nitride

Magnesium BromideMagnesium Bromide

Aluminum BromideAluminum Bromide

Iron(III) BromideIron(III) BromideFerric BromideFerric Bromide

Copper(I) BromideCopper(I) BromideCuprous BromideCuprous Bromide

Magnesium OxideMagnesium Oxide

Aluminum OxideAluminum Oxide

Iron(III) OxideIron(III) OxideFerric OxideFerric Oxide

Copper(I) OxideCopper(I) OxideCuprous OxideCuprous Oxide

Magnesium NitrideMagnesium Nitride

Aluminum NitrideAluminum Nitride

Iron(III) NitrideIron(III) NitrideFerric NitrideFerric Nitride

Copper(I) NitrideCopper(I) NitrideCuprous NitrideCuprous Nitride

21

Thanks to Christine Neighbors (Fall 2012)

22

Covalent BondsCovalent Bonds

H H+ H H

Cl

O

+ Cl Cl

O +

+N N N N

OO

Cl

23

Covalent BondsCovalent Bonds

H H

Cl Cl

N N

OO

H-H HH22 Cl-Cl ClCl22

O=O OO22

N N NN22

24

Covalent compoundsCovalent compounds

•Discrete molecular units

•Atoms held together by bonds

•Covalent compounds exist in all states(CO2 - gas, H2O - liquid, SiO2 - solid)

•Formula represents atoms in a molecule

Covalent compoundsCovalent compounds

O=O O=O

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O C

OC

Covalent BondsCovalent Bonds

O=C=O

C O

O

COCOCarbon Carbon monmonoxideoxide

Carbon Carbon didioxideoxide COCO22

May modify rules to improve the sound. ExampleExample - use monoxide not monooxide.

26

Naming Covalent CompoundsNaming Covalent Compounds

In the names of covalent compounds, prefixes are used to indicate the number of atoms (subscript) of each element. (mono is omitted for the first element, not the second)

Prefixes Used in Naming Covalent Compounds

27

Rules for Naming Binary Compounds Containing Two Nonmetals

1. Write the name of the first nonmetal as it appears on the periodic table. Use a prefix if there is more than one atom.

2. Use a prefix to indicate the number of atoms for the second nonmetal.

3. Write the stem of the second nonmetal. 4. Add the suffix –ide.

28

CO

CO2

Cl2O

N2O5

SiO2

ICl3

P2O5

CCl4

Naming covalent compoundsNaming covalent compounds

May modify rules to improve the sound. ExampleExample - use monoxide not monooxide.

carbon tetrachloride

diphosphorous pentoxide

iodine trichloride

silicon dioxide

carbon monoxide

carbon dioxide

dinitrogen pentoxidedichlorine monoxide

29

Bond Polarity, ElectronegativityBond Polarity, Electronegativity

ClH

Electrons in covalent bonds rarely get shared equally.

H Cl

ElectronegativityElectronegativityRelative ability of atoms to attract e-.

At

I

Br

Cl

Po

Te

Se

S

Bi

Sb

As

P

Pb

Sn

Ge

Si

FON

Tl

Na

Cs

Rb

K

Ba

Mg

Sr

Ca

In

Ga

Al

H

Li Be B C

ClH

1.0

0.8

0.9

1.5

1.2

0.7

1.0

2.0

1.5

0.8

1.0

0.9

1.6

1.7

1.8

2.5

1.8

1.8

1.8

1.9

3.0

2.1

2.0

1.9

1.9

3.5

2.5

2.4

2.1

2.0

4.0

3.0

2.8

2.5

2.1

2.1

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This unequal sharing results in polarpolar bonds.This unequal sharing results in polarpolar bonds.

H ClH Cl

•Slight positive side•Smaller electronegativity•Slight positive side•Smaller electronegativity

•Slight negative•Larger electronegativity•Slight negative•Larger electronegativity

++++ ––––

Bond Polarity, ElectronegativityBond Polarity, ElectronegativityClH

32

Bond Polarity, ElectronegativityBond Polarity, Electronegativity

H Cl+ –

This unequal sharing results in polarpolar bonds.This unequal sharing results in polarpolar bonds.

•Slight positive side•Smaller electronegativity•Slight positive side•Smaller electronegativity

•Slight negative side•Larger electronegativity•Slight negative side•Larger electronegativity

ClH

33

ClH

ClH2.12.1 3.03.0

––

Polar Covalent

++

Electronegativity Electronegativity DifferenceDifference

< 0.5< 0.5 Nonpolar Nonpolar

0.5-1.70.5-1.7 Polar Polar

>>1.81.8 Ionic Ionic

Bond Polarity, ElectronegativityBond Polarity, Electronegativity

34

CO O

Polarity, ShapePolarity, Shape

3.53.5 3.53.52.52.5

O=C=O++ ––––

Polar Covalent Bonds

Linear Shape (180Linear Shape (180oo))Linear Shape (180Linear Shape (180oo))

Electronegativity Electronegativity DifferenceDifference

< 0.5< 0.5 Nonpolar Nonpolar

0.5-1.70.5-1.7 Polar Polar

>>1.81.8 Ionic Ionic

Nonpolar CompoundNonpolar Compound

COCO22

35

Polar and Non-PolarPolar and Non-Polar

Thanks to Paula H. & Judy M. (Summer 1976)

36

CH H

O

Polarity, ShapePolarity, Shape

O=C=O++ ––––

e–’s in 2 directions = 180o

LinearLinear

e–’s in 3 directions = 120o

++

–– Trigonal planarTrigonal planar

Nonpolar CompoundNonpolar Compound

Polar CompoundPolar Compound

37

Polarity, ShapePolarity, Shape

CH HH

Cl

CH H

H

ClH

C

H

ClH

OH H

H-O-H

O

H

H

++

++––

++

––

e–’s in 4 directions = 109.5o

TetrahedralTetrahedral

BentBent

4 directions = 109.5o

38

Polarity, ShapePolarity, Shape

NH HH ++

--e–’s in 4 directions = 109.5o

PyramidalPyramidal

NH H

HH

NHH++

++

39

Some common geometriesSome common geometries e- directions arounde- directions aroundShape central atomShape central atom Example___ Example___ e- directions arounde- directions aroundShape central atomShape central atom Example___ Example___

Linear 2 O=C=O

Tetrahedral 4

HC

H

ClH

Trigonal Planar 3 C

H H

O

40

O

H H HH

H H

H

H

H

CN

Tetrahedral electron-pair Geometries

TetrahedralTetrahedralPyramidalPyramidalBentBent

Methane, CH4

4 bond pairsAmmonia, NH3

3 bond pairsWater, H2O2 bond pairs

109.5º

107º

105º

41

Molecular geometryMolecular geometry

Molecules have specific shapes.

•Determined by the number of electron pairs around the central atom

•Bonded and unbonded pairs

Geometry affects factors like polarity and solubility.

42

Geometry Geometry and polar moleculesand polar molecules

For a molecule to be polarFor a molecule to be polar- must have polar bonds- must have the proper geometry

CH4 non-polarCH3Cl polarCH2Cl2 polarCHCl3 polarCCl4 non-polar

WHY?WHY?

43

Polarity and solubilityPolarity and solubilitySolubilitySolubility The maximum amount of a solute

that dissolves in a given solvent

Depends on the forces of attraction between molecules - intermolecular

Types of intermolecular attractions most often encountered• Dipole-DipoleDipole-Dipole• Hydrogen bondingHydrogen bonding• Van der Wall forcesVan der Wall forces

General rule“Like dissolves likeLike dissolves like”

44

Boiling and melting pointsBoiling and melting points

Chemical Bond Mp Bp N2 Nonpolar -210 -196 O2 Nonpolar -219 -183 NH3 Polar -78 -33 H2O Polar 0 100NaCl IonicIonic 804 ?

Melting and Boiling pointsMelting and Boiling points

•Very high for ionic compounds

•Typically lower for covalent compounds