BONDINGChapters 4 & 12Chapters 4 & 12

Ionic vs. Covalent Bonds

IonicIonic result from the attraction result from the attraction

between opposite charges of between opposite charges of ions ions

CovalentCovalent result from sharing of electrons result from sharing of electrons

between atomsbetween atoms

The Octet Rule

Atoms will gain, lose, or share electrons Atoms will gain, lose, or share electrons to achieve a noble gas configurationto achieve a noble gas configuration

If the atom has 1-3 valence electrons, it will If the atom has 1-3 valence electrons, it will LOSE those electrons and become a positive LOSE those electrons and become a positive ion (CATION).ion (CATION).

If the atom has 5-7 valence electrons, it will If the atom has 5-7 valence electrons, it will GAIN electrons until it has EIGHT, becoming a GAIN electrons until it has EIGHT, becoming a negative ion (ANION).negative ion (ANION).

Practice Forming Ions Complete the table below for each of the atoms:Complete the table below for each of the atoms:

ATOMATOM# of # of

Valence Valence ElectronsElectrons

GAIN or GAIN or LOSE LOSE

electrons?electrons?IONION CATION or CATION or

ANION?ANION?

MagnesiumMagnesium

ChlorineChlorine

PotassiumPotassium

NitrogenNitrogen

OxygenOxygen

LithiumLithium

What are Ionic Compounds?

Compound made of only ionsCompound made of only ions Formed by the gaining or losing of electronsFormed by the gaining or losing of electrons Typically between a metal and a non-metalTypically between a metal and a non-metal

Ionic BondingIonic BondingA positively charged ion (anion) will be A positively charged ion (anion) will be

attracted to and will form a bond with a attracted to and will form a bond with a negatively charged ion (cation)negatively charged ion (cation)

The ions will exchange electrons to achieve The ions will exchange electrons to achieve their charge (and reach the noble gas their charge (and reach the noble gas configuration)configuration)

Ionic Attraction?

Properties of Ionic Compounds

Overall neutralOverall neutral High melting pointsHigh melting points Generally brittle solidsGenerally brittle solids Dissolve in water to form electrolytesDissolve in water to form electrolytes

Types of Ions

Monoatomic cationsMonoatomic cations Monoatomic anionsMonoatomic anions Polyatomic ionsPolyatomic ions

Monoatomic cations Positively charged, ions formed from ONE atomPositively charged, ions formed from ONE atom

To name the cation, simply add the word “ion” after the To name the cation, simply add the word “ion” after the element’s nameelement’s name

LiLi++ Lithium ionLithium ion MgMg+2+2 Magnesium ionMagnesium ion

Some atoms have the ability to form multiple ions Some atoms have the ability to form multiple ions (most of these are “transition” metals)(most of these are “transition” metals) To name, simply name the element, indicate the charge To name, simply name the element, indicate the charge

in roman numerals and then add the word “ion”in roman numerals and then add the word “ion” FeFe+2+2 Iron (II) ion Iron (II) ion FeFe+3+3 Iron (III) ion Iron (III) ion

Monoatomic anion

Negatively charged, ions formed from ONE Negatively charged, ions formed from ONE atomatom To name the anion, replace the ending of the To name the anion, replace the ending of the

element’s name with “-ide”element’s name with “-ide” F F -- FluorFluorineine Fluoride Fluoride O O -2-2 OxOxygenygen Oxide Oxide

Monoatomic ion Practice Complete the table below for each of the atoms:Complete the table below for each of the atoms:

ATOMATOM IONION

CATION CATION

or or

ANION?ANION?

NAME of IONNAME of ION

MagnesiumMagnesium

ChlorineChlorine

PotassiumPotassium

NitrogenNitrogen

OxygenOxygen

LithiumLithium

Polyatomic ions

Multiple atoms that, TOGETHER, carry Multiple atoms that, TOGETHER, carry a charge.a charge.

IONIC COMPOUNDS

WRITING FORMULASWRITING FORMULAS Write the symbol for the cation first.Write the symbol for the cation first. Write the symbol for the anion second.Write the symbol for the anion second. Add subscripts so the charges equal zero when Add subscripts so the charges equal zero when

added.added.

NAMING COMPOUNDSNAMING COMPOUNDS Write the name of the cation unchanged first.Write the name of the cation unchanged first. Write the root of the anion with the –ide ending.Write the root of the anion with the –ide ending.

How do I write a formula for an ionic compound?

Use the CRISS-CROSS METHOD:Use the CRISS-CROSS METHOD: Write the Write the ionsions in order of metal then nonmetal in order of metal then nonmetal Take the ionic charge number (written as the Take the ionic charge number (written as the

superscript) of each element and criss cross it to superscript) of each element and criss cross it to the subscript of the other elementthe subscript of the other element

CaCa ClCl+2+2 -1-1

CaCa__ClCl__2211

Ionic Compound Formula Practice

Write the ionic formula for the following ionsWrite the ionic formula for the following ions

MgMg+2+2 with P with P-3 -3

BB+3+3 with S with S-2-2

LiLi+1+1 with S with S-2 -2

GaGa+3+3 with Se with Se-2 -2

BB+3+3 with At with At-1 -1

How do I name ionic compounds?

Compounds are named from the ions that form Compounds are named from the ions that form them…them… The first element (metal) keeps its nameThe first element (metal) keeps its name

If it’s a transition metal, you must use a roman numeral to If it’s a transition metal, you must use a roman numeral to indicate its chargeindicate its charge

The second element (nonmetal) keeps the first syllable of The second element (nonmetal) keeps the first syllable of its name and the ending is changed to “-ide”its name and the ending is changed to “-ide”

NaClNaCl

Sodium ChlorideSodium Chloride

FeFe22OO33Since Fe is a transition metal, you must find its

charge… UNCRISS CROSS

FeFe22OO33

FeFe OO+3+3 -2-2Iron (III)Iron (III) OxideOxide

Ionic Compound Naming Practice

Write the ionic compound name for the Write the ionic compound name for the following…following…

BaClBaCl22

NaFNaF

AgAg22OO

CuBrCuBr

CuBrCuBr22

Binary Ionic Compounds

Binary Binary Compound Compound

Ionic Ionic compound compound composed of composed of two atomstwo atoms

Formula UnitFormula Unit Smallest Smallest

representative representative unitunit

ATOMSATOMS FORMULAFORMULA NAME of NAME of COMPOUNDCOMPOUND

Magnesium & ChlorineMagnesium & Chlorine

IONS:IONS:

Potassium & NitrogenPotassium & Nitrogen

IONS:IONS:

Lithium & OxygenLithium & Oxygen

IONS:IONS:

Tertiary Ionic Compounds

Tertiary Tertiary Compound Compound

Ionic Ionic compound compound composed of composed of three atomsthree atoms

IONSIONS FORMULAFORMULA NAME of NAME of COMPOUNDCOMPOUND

KK++ and NO and NO33--

MgMg+2+2 and OH and OH--

CuCu+2+2 and PO and PO44-3-3

Hydrates

Ionic Ionic compounds compounds that absorb that absorb water into their water into their solid structuressolid structures

CuSOCuSO44 ●● 5H 5H22OO

PREFIXPREFIX NUMBERNUMBER

mono-mono- 11

di-di- 22

tri-tri- 33

tetra-tetra- 44

penta-penta- 55

hexa-hexa- 66

hepta-hepta- 77

octa-octa- 88

nona-nona- 99

deca-deca- 1010

Copper Sulfate PentahydrateCopper Sulfate Pentahydrate

Covalent Compounds

Covalent BondCovalent Bond Formed by the sharing of electronsFormed by the sharing of electrons

MoleculeMolecule Smallest representative unitSmallest representative unit

Molecular CompoundMolecular Compound Compounds composed of moleculesCompounds composed of molecules

Molecular FormulaMolecular Formula Shows the kind and numbers of atoms Shows the kind and numbers of atoms

present in a moleculepresent in a molecule

Properties of Covalent Compounds

made of two nonmetalsmade of two nonmetals low melting and boiling pointslow melting and boiling points solid, liquid, or gas at room temp.solid, liquid, or gas at room temp. do not dissociate in waterdo not dissociate in water

Naming Covalent Compounds

1. Write the less electronegative element first.2. Write the root of the more electronegative element with the -

ide ending second.REVIEW: Electronegativity - the attraction to electrons involved in a

chemical bond

3. Add prefixes to both indicating the number of atoms of each element

Exceptions when Naming Covalent Compounds

Exceptions:Exceptions:1. Do not use mono-with the first element in the

compound

2. Prefixes are sometimes shortened.

CO (Carbon Monoxide)

3. Chemist use common names for some compounds other than the formal names.

NH3 (Ammonia)

Naming Covalent Compounds

FORMULAFORMULA NAME of COMPOUNDNAME of COMPOUND

COCO

COCO22

COCO33-2-2

CC22OO44-2-2

Types of Covalent Bonds Polar Covalent BondPolar Covalent Bond

one atom in a molecule is significantly more one atom in a molecule is significantly more electronegativeelectronegative

causes a slight positive and negative charge on a causes a slight positive and negative charge on a molecule.molecule.

Nonpolar Covalent BondNonpolar Covalent Bond electrons are shared equallyelectrons are shared equally

Electronegativity DifferencesElectronegativity Differences Bond TypeBond Type 0.40.4 nonpolar nonpolar

0.5-1.90.5-1.9 polar polar 2.02.0 ionic ionic

Covalent Bonds

Single Covalent BondSingle Covalent Bond two atoms share 1 pair of electronstwo atoms share 1 pair of electrons

Double Covalent BondDouble Covalent Bond two atoms share 2 pair of electronstwo atoms share 2 pair of electrons

Triple Covalent BondTriple Covalent Bond two atoms share 3 pair of electronstwo atoms share 3 pair of electrons

Acid

A molecular substance that dissolves in water to A molecular substance that dissolves in water to produce a hydrogen ion produce a hydrogen ion

Acts like an ionic compound because they break Acts like an ionic compound because they break down into cations and anions in waterdown into cations and anions in water

Produces a characteristic anion for which it is Produces a characteristic anion for which it is named. named.

If the anion ends with If the anion ends with --ideide (i.e. chloride or fluoride)(i.e. chloride or fluoride)

Add the prefix hydro- and change the ending to –ic and add the word Add the prefix hydro- and change the ending to –ic and add the word acidacid

-ate-ate (i.e. phosphate or sulfate)(i.e. phosphate or sulfate) Change the ending to –ic and add the word acidChange the ending to –ic and add the word acid

-ite-ite (i.e. sulfite and phosphite)(i.e. sulfite and phosphite) Change the ending to –ous and add the word acidChange the ending to –ous and add the word acid