Chemical Bonds Chemical Bonds

Physical SciencePhysical Science

Valence Valence ElectronsElectrons

Electrons found in the Electrons found in the last shell, orbital or last shell, orbital or energy levelenergy level

Code :Code : 1,2,3,4,5,6,7,81,2,3,4,5,6,7,8

““A” columnsA” columns

Electron Dot DiagramsElectron Dot Diagrams

An An electron dot diagramelectron dot diagram is a model of an is a model of an atom in which each dot represents a atom in which each dot represents a valence electron. valence electron.

Stable configuration—eight valence Stable configuration—eight valence electronselectrons

Electron Dot PracticeElectron Dot Practice

1.1.He He _2_VE_2_VE

2.2.C C _4_VE_4_VE

3.3.Ca Ca _2_VE_2_VE

4.4.Na Na _1_VE_1_VE

5.5.Cl Cl _7_VE_7_VEVE= valence electrons

Valence Numbers/Oxidation NumbersValence Numbers/Oxidation NumbersNumber of electrons that the element will gain Number of electrons that the element will gain or lose to become stable.or lose to become stable.

Code:Code:+1,+2, +3, +/-4, -3, -2,-1,0+1,+2, +3, +/-4, -3, -2,-1,0

A columns onlyA columns only

IONSIONSCharged ParticlesCharged Particles

AnionAnion—an ion with a —an ion with a negative chargenegative charge

CationCation—an ion with a —an ion with a positive chargepositive charge

Goal of ALL ElementsGoal of ALL Elements

To have To have 88 electrons or the last electrons or the last shell full.shell full.

Which family is stable?Which family is stable?Nobel Gases (Inert Gases)Nobel Gases (Inert Gases)

Chemical BondingChemical Bonding

Chemical BondChemical Bond::– 2 or more elements 2 or more elements

chemically combine chemically combine to form a to form a compound.compound.

– The force holding The force holding atoms or ions atoms or ions togethertogether

Types of BondsTypes of Bonds

IonicIonic CovalentCovalent MetallicMetallic

Electrons are Electrons are gained or lost gained or lost

Electrons are Electrons are shared shared

Electrons are Electrons are gained or lostgained or lost

Metal and Metal and nonmetalnonmetal

EX: Table saltEX: Table salt

Nonmetal and Nonmetal and nonmetalnonmetal

EX: Water or EX: Water or sugarsugar

Metal and metalMetal and metal

EX: Any alloysEX: Any alloys

Properties and Arrangements in Properties and Arrangements in Ionic BondsIonic Bonds

PropertiesPropertiesIonization-Ionization- process of process of

elements losing elements losing electrons. (metals)electrons. (metals)

1A, 2A, 3A1A, 2A, 3A

Electron Affinity Electron Affinity – – process of elements process of elements gaining electrons. gaining electrons. (nonmetals)(nonmetals)

5A, 6A, 7A5A, 6A, 7A

Arrangement of IonsArrangement of Ions

Ratio shows equal Ratio shows equal proportionsproportions

Crystal shapeCrystal shape

Properties of Properties of Covalent BondsCovalent BondsShare electronsShare electrons

HH22 – Smallest covalent bond – Smallest covalent bond

knownknown

How do I write covalent How do I write covalent bonds?bonds?

H:H Electron Dot H:H Electron Dot ConfigurationConfiguration

Dots represent the electrons shared in Dots represent the electrons shared in

the bondthe bond

Diatomic AtomsDiatomic Atoms“Super Seven”“Super Seven”

DiDi means two. means two.

Definition: Definition: Elements combine Elements combine with itselfwith itself

Members of the Members of the “super seven”: “super seven”: Group 7A plus H, Group 7A plus H, N, and ON, and O

HH22

NN22

OO22

FF22

ClCl22

BrBr22

II22

Polyatomic IonsPolyatomic Ions

PolyPoly means many. means many.Definition: Compound acting as a Definition: Compound acting as a single charged element.single charged element.Examples:Examples: NHNH4 4 Ammonium Ammonium C C22HH33OO22 AcetateAcetate ClO ClO33 Chlorate OH Chlorate OH HydroxideHydroxide NO NO33 Nitrate Nitrate CO CO33 CarbonateCarbonate

SOSO44 Sulfate Sulfate PO PO44 PhosphatePhosphate

Element – Compounds - FormulasElement – Compounds - Formulas

ElementElementA particle A particle

that cannot that cannot be broken be broken down into down into

smaller smaller particlesparticles

CarbonCarbon

SymbolSymbol

Letters that Letters that represent represent

an elementan element

CC

CompoundCompound

Two or Two or more more

elements elements that that

chemically chemically combinecombine

Sodium Sodium chloridechloride

FormulasFormulas

Letters that Letters that represent a represent a compoundcompound

NaClNaCl

Bond ComparisonBond ComparisonBondsBonds Melting Melting

PointPointValence Valence

ElectronsElectronsElements Elements InvolvedInvolved

IonicIonic High High Melting PtMelting Pt

Gain or Gain or Lose Lose

ElectronsElectrons

Metals and Metals and NonmetalsNonmetals

CovalentCovalent Low Low Melting PtMelting Pt

Share Share ElectronsElectrons

Nonmetals Nonmetals and and

NonmetalsNonmetals

MetallicMetallic High High Melting PtMelting Pt

Free Free FlowingFlowing

ElectronsElectrons

Metals and Metals and MetalsMetals

Naming Compounds (Binary)Naming Compounds (Binary)Binary- 2 elementsBinary- 2 elements1.1.First First element is its element is its namename

2.2.SecondSecond element ends in element ends in –ide–ide

3.3.CombineCombine them together them together

NaClNaCl

Sodium ChlorSodium Chlorideide

Naming Compounds (Polyatomic)

Polyatomic- more than two elements.Polyatomic- more than two elements.1.1. First First element is its element is its namename

2.2. Name Name the the polyatomic ionpolyatomic ion

3. 3. CombineCombine together together

KNOKNO33

Potassium NitrPotassium Nitrateate

Key Thoughts for Naming

Never change the ending of a polyatomic

Change the ending of the single element only if it is the second element (-ide)

Practice in namingPractice in naming

KClKCl

MgOMgO

KClOKClO33

KCKC22HH33OO22

NHNH44NONO33

Potassium chlorPotassium chlorideide

Magnesium oxMagnesium oxideide

Potassium chlorPotassium chlorateate

Potassium acetPotassium acetateate

Ammonium nitrAmmonium nitrateate

Valence Numbers Valence Numbers Know the CodeKnow the Code

Valence NumbersValence Numbers are also known as are also known as OxidationOxidationnumbersnumbers

How many electrons an element will gain or lose to How many electrons an element will gain or lose to be stable.be stable.

Codes: Codes:

1A= +11A= +1 5A= –35A= –32A= +22A= +2 6A= –26A= –23A= +33A= +3 7A= –17A= –14A= +/- 44A= +/- 4 8A= 08A= 0

Writing and Balancing FormulasWriting and Balancing FormulasRulesRules

1.1. Write the Write the symbolssymbols

2.2. Write the Write the Valence #Valence # above each element.above each element.

3.3. See if the valence See if the valence number = number = 00. .

4.4. If not then cross over If not then cross over and write the oxidation and write the oxidation numbers as subscripts. numbers as subscripts. Don’t worry about the Don’t worry about the negative sign.negative sign.

Practice ProblemsPractice Problems

1.1. Mg ClMg Cl

2.2. K POK PO44

3.3. NHNH4 4 SOSO44

4.4. Sodium OxideSodium Oxide

AnswersAnswers

MgClMgCl22

KK33POPO44

(NH(NH44))22SOSO44

NaNa22OO

Formula and Naming with Weird Compounds

If using a transitional metal in naming, the charge of the metal is in parenthesis.

Covalent Bonds need to use prefixes– Ex: Carbon Dioxide = CO2