chapter 8 bonding. lewis structures diagram that shows diagram that shows american chemist gilbert...

Chapter 8Chapter 8

BondingBonding

Lewis StructuresLewis Structures

Diagram that shows Diagram that shows American chemist Gilbert N. LewisAmerican chemist Gilbert N. Lewis Dots = Dots =

Paired dots = Paired dots = Simple way of showing electronsSimple way of showing electrons Most reactions involve only Most reactions involve only

Lewis StructuresLewis Structures

When drawing:When drawing: Use electron configurationUse electron configuration Move in clockwise direction…Move in clockwise direction… ““12” = s orbital12” = s orbital ““3, 6, 9” = p orbitals – fill each with ONE 3, 6, 9” = p orbitals – fill each with ONE

electron before filling with pairs…electron before filling with pairs… Just like orbital filling diagram…Just like orbital filling diagram…

Examples: draw Lewis Structures of B, N, Examples: draw Lewis Structures of B, N, F, NeF, Ne

The Ionic BondThe Ionic Bond Ionic bond: Ionic bond:

Transfer of electrons from Transfer of electrons from Ions form with Ions form with Attraction between electrostatic charges Attraction between electrostatic charges

is a strong forceis a strong force which holds which holds

atoms atoms togethertogether

The Ionic BondThe Ionic Bond NOT A NOT A

Bond not just Bond not just between (for between (for example) one example) one sodium and one sodium and one chloridechloride

The Ionic BondThe Ionic Bond

Typically Typically Metals usually Metals usually Nonmetals usually Nonmetals usually

Predicting Formulas of Ionic Predicting Formulas of Ionic CompoundsCompounds

In almost all stable chemical In almost all stable chemical compounds of representative compounds of representative elements, each atom attains a elements, each atom attains a

This concept forms the basis for our This concept forms the basis for our understanding of chemical bonding.understanding of chemical bonding.


How many electrons must be gained How many electrons must be gained or lost to achieve noble gas or lost to achieve noble gas configuration?configuration? Ba must lose Ba must lose

Forms the ion Forms the ion S must gain S must gain

Forms the ion Forms the ion So…must be ratio of So…must be ratio of


Elements in a family usually form Elements in a family usually form compounds with the same atomic compounds with the same atomic ratiosratios Because they have the same number of Because they have the same number of

valence electronsvalence electrons Must gain or lose the same number of Must gain or lose the same number of

electronselectrons See table 11.4 pg 233See table 11.4 pg 233


The formula for sodium oxide is The formula for sodium oxide is NaNa22O. Predict the formula for O. Predict the formula for Sodium sulfide Sodium sulfide


Rubidium OxideRubidium Oxide Rubidium Rubidium Oxygen Oxygen So…formula must be So…formula must be This makes sense b/c rubidium is in This makes sense b/c rubidium is in

same family as sodiumsame family as sodium

The Covalent BondThe Covalent Bond A pair of A pair of Most common type of bondMost common type of bond Stronger than Stronger than Electron orbital expands to include both Electron orbital expands to include both

nucleinuclei most often foundmost often found between between

Negative chargesNegative charges

allow positive nucleiallow positive nuclei to be drawn close to be drawn close

to each other to each other

The Covalent BondThe Covalent Bond

Atoms may share more than one pair of Atoms may share more than one pair of electronselectrons Double bond – Double bond – Triple bond – Triple bond – Multiple bonds are Multiple bonds are

Covalent bonding between identical atoms Covalent bonding between identical atoms

means electrons are shared means electrons are shared Covalent bonding between different atoms Covalent bonding between different atoms

leads to leads to

ElectronegativityElectronegativity

The attractive force that an atom of The attractive force that an atom of an element has for an element has for

Atoms have different Atoms have different electronegativitieselectronegativities Electrons will spend more time near Electrons will spend more time near

atom with atom with So…one atom assumes a partial So…one atom assumes a partial The other assumes a partial The other assumes a partial


Electronegativity trends and periodic Electronegativity trends and periodic tabletable See table 11.5 page 237See table 11.5 page 237 Generally increases from Generally increases from Decreases Decreases Highest is Highest is Lowest is Lowest is

ElectronegativityElectronegativity Polarity is determined by Polarity is determined by

difference in electronegativitydifference in electronegativity Nonpolar covalentNonpolar covalent

Polar covalentPolar covalent

Ionic compoundIonic compound


If the electronegativity difference is If the electronegativity difference is greater thangreater than

Above Above Below Below


Polar bonds form between two atomsPolar bonds form between two atoms Molecules can also be polar or nonpolarMolecules can also be polar or nonpolar

DipoleDipole

PolarPolar

NonpolarNonpolar

Lewis Structures of Lewis Structures of CompoundsCompounds

Convenient way of showing ionic or Convenient way of showing ionic or covalent bondscovalent bonds

Usually the single atom in a formula Usually the single atom in a formula is the central atomis the central atom

The Ionic BondThe Ionic Bond LEWIS STRUCTURES of ionic bondsLEWIS STRUCTURES of ionic bonds

The Covalent BondThe Covalent Bond LEWIS STRUCTURES of covalent LEWIS STRUCTURES of covalent

bondsbonds Use dashes instead of dots…Use dashes instead of dots…

The Covalent BondThe Covalent Bond


1)1) Obtain the total number of valence Obtain the total number of valence electronselectrons

1)1) Add the valance electrons of all atomsAdd the valance electrons of all atoms

2)2) Ionic – add one electron for each Ionic – add one electron for each negative charge and subtract one negative charge and subtract one electron for each positive chargeelectron for each positive charge


2)2) Write the skeletal arrangement of Write the skeletal arrangement of the atoms and connect with a single the atoms and connect with a single covalent vondcovalent vond

3)3) Subtract two electrons for each Subtract two electrons for each single bond single bond

1)1) This gives you the net number of This gives you the net number of electrons available for completing the electrons available for completing the structurestructure


4)4) Distribute pairs of electrons around Distribute pairs of electrons around each atom to give each atom a each atom to give each atom a noble gas structurenoble gas structure

5)5) If there are not enough electrons If there are not enough electrons then try to form double and triple then try to form double and triple bonds bonds

Lewis Structures of Lewis Structures of Compounds Compounds

Write the Lewis Structure for Write the Lewis Structure for methane CHmethane CH44


Carbon Dioxide, COCarbon Dioxide, CO22

Complex Lewis StructuresComplex Lewis Structures

Some molecules and polyatomic ions Some molecules and polyatomic ions have strange behaviors…have strange behaviors… No single Lewis structure is consistentNo single Lewis structure is consistent If multiple structures are possible the If multiple structures are possible the

molecule showsmolecule shows

Complex Lewis StructuresComplex Lewis Structures

Carbonate ion, COCarbonate ion, CO332-2-

Compounds ContainingCompounds ContainingPolyatomic IonsPolyatomic Ions

Polyatomic ion: Polyatomic ion:

Behaves as a single unit in many Behaves as a single unit in many chemical reactionschemical reactions

Sodium carbonate (NaSodium carbonate (Na22COCO33))

chapter 8 bonding. lewis structures diagram that shows diagram that shows american chemist gilbert...

Documents

ionic bond ionic bond

sodium slide

bonding slide

ne slide

ratio of slide

atomstogether slide

chloride slide

number of electrons