COVALENT BONDING

COVALENT COVALENT BONDINGBONDING

Chapter 16Chapter 16

AND THE SUBJECTS ARE…AND THE SUBJECTS ARE…

THE NAME IS BOND, COVALENT BONDTHE NAME IS BOND, COVALENT BOND

SINGLES, DOUBLES & TRIPPPLESSINGLES, DOUBLES & TRIPPPLES

COORDINATE COVALENT BONDSCOORDINATE COVALENT BONDS

RESONATE THIS!RESONATE THIS!

THERE’S ALWAYS AN EXCEPTIONTHERE’S ALWAYS AN EXCEPTION

PRINCESS VSEPRPRINCESS VSEPR

HYBRIDS HYBRIDS

DISSOCIATIONS AND ATTRACTIONSDISSOCIATIONS AND ATTRACTIONS

YOU KNOW THAT YOU MAY YOU KNOW THAT YOU MAY BE A COVALENT BOND BE A COVALENT BOND

WHEN…WHEN…

ELECTROSTATIC FORCES ARE WEAKELECTROSTATIC FORCES ARE WEAK

ELECTRONEGATIVITY IS SMALLELECTRONEGATIVITY IS SMALL

THERE ARE NO METAL CATIONSTHERE ARE NO METAL CATIONS

IONS DON’T GET OR LOSE ELECTRONSIONS DON’T GET OR LOSE ELECTRONS

SINGLE COVALENT BONDSINGLE COVALENT BOND

HYDROGENHYDROGEN

HH· + ·H · + ·H H:H H:HHydrogen Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen

Atom Atom moleculeAtom Atom molecule

HYDROGEN ATOMS FORM SINGLE BONDSHYDROGEN ATOMS FORM SINGLE BONDS

Shared electron pair


DIATOMIC MOLECULESDIATOMIC MOLECULES

HYDROGENHYDROGEN NITROGEN NITROGEN OXYGEN OXYGEN FLUORINE FLUORINE CHLORINECHLORINE BROMINEBROMINE

IODINEIODINE

ELECTRONEGATIVITY = 0ELECTRONEGATIVITY = 0

SHARED ELECTRONSSHARED ELECTRONS

FOR CHLORINE,FOR CHLORINE,

1s 2s 2p1s 2s 2p 3s 3p 3s 3p

ClCl ↑↓↑↓ ↑↓↑↓ ↑↓↑↓ ↑↓↑↓ ↑↓↑↓ ↑↓↑↓ ↑↓↑↓ ↑↓↑↓ ↑_↑_

ClCl ↑↓↑↓ ↑↓↑↓ ↑↓↑↓ ↑↓↑↓ ↑↓↑↓ ↑↓↑↓ ↑↓↑↓ ↑↓↑↓ _↓_↓


SINGLE COVALENT BONDSINGLE COVALENT BONDDEFINITIONSDEFINITIONS

EMPIRICAL FORMULAEMPIRICAL FORMULA - LOWEST WHOLE - LOWEST WHOLE NUMBER RATIO OF ELEMENTS IN A NUMBER RATIO OF ELEMENTS IN A COMPOUNDCOMPOUND

MOLECULAR FORMULAMOLECULAR FORMULA – SHOWS ACTUAL – SHOWS ACTUAL NUMBER AND KINDS OF ELEMENTS IN A NUMBER AND KINDS OF ELEMENTS IN A COMPOUNDCOMPOUND

STRUCTURAL FORMULASTRUCTURAL FORMULA – SHOWS – SHOWS ARRANGEMENT OF ATOMS IN A ARRANGEMENT OF ATOMS IN A COMPOUNDCOMPOUND



ELECTRON PAIRS REPRESENTED BY A ELECTRON PAIRS REPRESENTED BY A LINE BETWEEN 2 ELEMENTSLINE BETWEEN 2 ELEMENTS

H - HH - HOTHER ELECTRONS MUST BE SHOWN, OTHER ELECTRONS MUST BE SHOWN,

INCLUDINGINCLUDINGUNSHARED PAIRSUNSHARED PAIRSLONE PAIRSLONE PAIRSNON-BONDING PAIRSNON-BONDING PAIRS


2 CHLORINE ATOMS FORM A 2 CHLORINE ATOMS FORM A COVALENT BONDCOVALENT BOND

WATER MOLECULE FORMED FROM 1 WATER MOLECULE FORMED FROM 1 OXYGEN AND 2 HYDROGEN ATOMS OXYGEN AND 2 HYDROGEN ATOMS

USING COVALENT BONDSUSING COVALENT BONDS



CARBON FORMS UP TO 4 BONDSCARBON FORMS UP TO 4 BONDS

CC ↑↓↑↓ ↑↓↑↓ ↑_↑_ ↑_↑_

1s 2s 2p1s 2s 2p

TO MAKE THE 4TO MAKE THE 4THTH BOND, A 2s ELECTRON BOND, A 2s ELECTRON MOVES TO A 2p ORBITALMOVES TO A 2p ORBITAL

CC ↑↓↑↓ ↑_↑_ ↑_↑_ ↑_↑_ ↑_↑_

1s 2s 1s 2s 2p 2p

DOUBLE AND TRIPLE DOUBLE AND TRIPLE COVALENT BONDSCOVALENT BONDS

CORDINATE COVALENT CORDINATE COVALENT BONDSBONDS

BOND FORMED WHEN BOTH ELECTRONS BOND FORMED WHEN BOTH ELECTRONS DONATED BY THE SAME ATOMDONATED BY THE SAME ATOM

POLYATOMIC IONSPOLYATOMIC IONS

POLYATOMIC IONS ARE POLYATOMIC IONS ARE COVALENTLY BONDEDCOVALENTLY BONDED

THE CHARGE ON THE ION SHOWS THE CHARGE ON THE ION SHOWS THE NUMBER OF ELECTRONS THE NUMBER OF ELECTRONS

ADDED OR MISSINGADDED OR MISSING

RESONANCERESONANCE

RESONANCE STRUCTURES SHOW 2 OR RESONANCE STRUCTURES SHOW 2 OR MORE VALID DOT FORMULAS HAVING MORE VALID DOT FORMULAS HAVING THE SAME NUMBER OF BONDS AND THE SAME NUMBER OF BONDS AND

ELECTRONSELECTRONS

EXCEPTIONS to the EXCEPTIONS to the OCTET RULEOCTET RULE

IN SOME MOLECULES, THE OCTET IN SOME MOLECULES, THE OCTET RULE CANNOT BE SATISFIEDRULE CANNOT BE SATISFIED

EXCEPTIONS to the OCTET EXCEPTIONS to the OCTET RULERULE

DIAMAGNETICDIAMAGNETIC – ALL – ALL ELECTRONS PAIREDELECTRONS PAIRED

PARAMAGNETICPARAMAGNETIC - 1 OR - 1 OR MORE UNPAIRED MORE UNPAIRED ELECTRONSELECTRONS

EXPANDED OCTETEXPANDED OCTET – – MAY INCLUDE MORE MAY INCLUDE MORE THAN 8 ELECTRONSTHAN 8 ELECTRONS

MOLECULAR ORBITALS (MO)MOLECULAR ORBITALS (MO)

WHEN 2 ATOMIC ORBITALS OVERLAP,

2 MOLECULAR ORBITALS FORM1 ORBITAL IS BONDING

ENERGY LOWER THAN ATOMIC ORBITAL

1 ORBITAL IS ANTI-BONDING

ENERGY HIGHER THAN ATOMIC ORBITAL

ORBITAL BELONGS TO MOLECULE AS A WHOLE

ORBITAL CONTAINS UP TO 2 ELECTRONS

MOLECULAR ORBITALSMOLECULAR ORBITALSEnerg

y

Atomic Orbital

Atomic Orbital

Anti-bonding Molecular Orbital

Bonding Molecular Orbital

MOLECULAR ORBITALSMOLECULAR ORBITALSHYDROGENHYDROGEN

TWO HTWO H22 MOLECULE ELECTRONS MOLECULE ELECTRONS OCCUPY A BONDING ORBITAL OCCUPY A BONDING ORBITAL

PROBABILITY OF FINDING ELECTRONS PROBABILITY OF FINDING ELECTRONS IN THE AREA BETWEEN 2 ATOMS IS IN THE AREA BETWEEN 2 ATOMS IS HIGHHIGH

BOND IS SYMETRICAL ALONG AXIS BOND IS SYMETRICAL ALONG AXIS BETWEEN ATOMSBETWEEN ATOMS

CALLED A SIGMA (CALLED A SIGMA (σσ) BOND) BOND


y

Atomic Orbital

Atomic Orbital



H2

MOLECULAR ORBITALS (MO)MOLECULAR ORBITALS (MO)

MOLECULAR ORBITALSMOLECULAR ORBITALSHELIUMHELIUM

2 MOLECULES OF He CANNOT BE FORMED2 MOLECULES OF He CANNOT BE FORMED

2 ELECTRONS IN BONDING ORBITAL2 ELECTRONS IN BONDING ORBITAL

2 ELECTRONS IN ANTI-BONDING ORBITAL2 ELECTRONS IN ANTI-BONDING ORBITAL

REPULSIVE FORCES IN ANTI-BONDING REPULSIVE FORCES IN ANTI-BONDING ORBITAL NEGATES ATTRACTIVE ORBITAL NEGATES ATTRACTIVE FORCES IN BONDING ORBITALFORCES IN BONDING ORBITAL


y

Atomic Orbital

Atomic Orbital



He

MOLECULAR ORBITALSMOLECULAR ORBITALS

““p” ORBITALS CAN OVERLAPp” ORBITALS CAN OVERLAP

OVERLAP END-TO-END – SIGMA (OVERLAP END-TO-END – SIGMA (σσ) BOND) BOND

OVERLAP SIDE-BY-SIDE – PI (OVERLAP SIDE-BY-SIDE – PI ( BOND BOND



VVALENCE ALENCE SSHELL HELL EELECTRON LECTRON PPAIR AIR RREPULSION THEORYEPULSION THEORY

VSEPRVSEPR

ELECTRON PAIRS REPEL DUE TO THE ELECTRON PAIRS REPEL DUE TO THE SAME CHARGESAME CHARGE

MOLECULAR SHAPE ADJUSTS TO SET MOLECULAR SHAPE ADJUSTS TO SET FURTHEST DISTANCE BETWEEN PAIRSFURTHEST DISTANCE BETWEEN PAIRS

CREATES 3 DIMENSIONAL STRUCTURESCREATES 3 DIMENSIONAL STRUCTURES

MOLECULES in 3-DMOLECULES in 3-D

METHANE (CHMETHANE (CH44))

CARBON in CENTER, CARBON in CENTER, with H in the with H in the CORNERS to form a CORNERS to form a TETRAHEDRONTETRAHEDRON

H-C-H ANGLES ARE H-C-H ANGLES ARE 109.5°109.5°

MOLECULES in 3-DMOLECULES in 3-DMOLECULAR GEOMETRY


UNSHARED ELECTRON UNSHARED ELECTRON PAIRS IMPACT SHAPEPAIRS IMPACT SHAPE

UNSHARED ELECTRONS UNSHARED ELECTRONS HELD CLOSER TO HELD CLOSER TO NUCLEUSNUCLEUS

UNSHARED ELECTRONS UNSHARED ELECTRONS ALSO MORE ALSO MORE STRONGLY REPEL STRONGLY REPEL OTHER ATOMSOTHER ATOMS ANGLE SHIFTS TO 107°


DIHYDROGEN OXIDE (HDIHYDROGEN OXIDE (H22O)O)

MOLECULE BECOMES BENT MOLECULE BECOMES BENT PLANAR WITH 2 PAIRS PLANAR WITH 2 PAIRS UNSHARED ELECTRONSUNSHARED ELECTRONS

UNSHARED PAIRS REPEL UNSHARED PAIRS REPEL BONDING PAIRS, BONDING PAIRS, COMPRESSING ANGLECOMPRESSING ANGLE

H-O-H ANGLE IS 105°H-O-H ANGLE IS 105°


CARBON DIOXIDE (COCARBON DIOXIDE (CO22))

NO UNSHARED NO UNSHARED ELECTRON PAIRS IN ELECTRON PAIRS IN CARBON DIOXIDECARBON DIOXIDE

MOLECULE IS LINEARMOLECULE IS LINEAR

ANGLE IS 180o


MOLECULES WITH NO MOLECULES WITH NO UNPAIRED UNPAIRED ELECTRONS, BUT ELECTRONS, BUT WITH DOUBLE BONDWITH DOUBLE BOND

MOLECULE IS MOLECULE IS TRIAGONAL PLANAR TRIAGONAL PLANAR SHAPESHAPE

HYBRID ORBITALSHYBRID ORBITALS

SEVERAL ATOMIC SEVERAL ATOMIC ORBITALS CAN MIX ORBITALS CAN MIX TO FORM HYBRID TO FORM HYBRID ORBITALSORBITALS

EACH ATOM HAS EACH ATOM HAS SEPARATE s AND p SEPARATE s AND p ORBITALSORBITALS


SOME ATOMIC SOME ATOMIC ORBITALS MERGE, ORBITALS MERGE, FORMING 4 spFORMING 4 sp33 HYBRID ORBITALSHYBRID ORBITALS

EACH ORBITAL EACH ORBITAL BENDS TOWARD BENDS TOWARD CORNER OF CORNER OF TETRAHEDRONTETRAHEDRON


METHANE (CHMETHANE (CH44))

s ORBITALS OF s ORBITALS OF HYDROGEN OVERLAP HYDROGEN OVERLAP CARBON spCARBON sp33 ORBITAL ORBITAL

FORMS FORMS σσ BONDS BONDS


DOUBLE BONDSDOUBLE BONDS

ATOMIC ORBITALS IN ATOMIC ORBITALS IN DOUBLE BONDS DOUBLE BONDS MERGE TO FORM 3 spMERGE TO FORM 3 sp22 HYBRID ORBITALS & 1 HYBRID ORBITALS & 1 p ORBITAL REMAINSp ORBITAL REMAINS

ORBITALS BEND ORBITALS BEND TOWARD CORNER OF TOWARD CORNER OF TRIANGLE, TRIANGLE, PERPENDICULAR TO PERPENDICULAR TO REMAINING p ORBITALREMAINING p ORBITAL


ETHYLENE (CETHYLENE (C22HH44))

HYDROGEN ORBITALS HYDROGEN ORBITALS OVERLAP WITH OVERLAP WITH CARBON spCARBON sp22 ORBITALS ORBITALS

1 sp1 sp22 ORBITAL FROM ORBITAL FROM EACH CARBON BONDSEACH CARBON BONDS

REMAINING CARBON p REMAINING CARBON p ORBITALS FORM A ORBITALS FORM A BONDBOND


TRIPLE BONDSTRIPLE BONDS

ATOMIC ORBITALS ATOMIC ORBITALS MERGE TO FORM 2 sp MERGE TO FORM 2 sp HYBRID ORBITALS, AND HYBRID ORBITALS, AND 2 p ORBITALS REMAIN2 p ORBITALS REMAIN

ORBITAL IS LINEAR AND ORBITAL IS LINEAR AND PERPENDICULAR TO PERPENDICULAR TO REMAINING p ORBITALSREMAINING p ORBITALS

HYBRID ORBITALSHYBRID ORBITALSACETYLENE (CACETYLENE (C22HH22))

HYDROGEN s ORBITALS HYDROGEN s ORBITALS OVERLAP WITH OVERLAP WITH CARBON spCARBON sp22 ORBITALS, ORBITALS, AND 1CARBON spAND 1CARBON sp22 ORBITAL EACH BONDORBITAL EACH BOND

REMAINING CARBON p REMAINING CARBON p ORBITALS FORM ORBITALS FORM BONDBOND

POLAR BONDSPOLAR BONDS

BOND POLARITYBOND POLARITYELECTRONS SHARED IN COVALENT BONDELECTRONS SHARED IN COVALENT BOND

BUT NOT NECESSARILY EQUALLYBUT NOT NECESSARILY EQUALLY

NON-POLAR BONDSNON-POLAR BONDSELECTRONS SHARED EQUALLYELECTRONS SHARED EQUALLY

POLAR BONDPOLAR BONDELECTRONS PULLED STRONGLY TO ATOM ELECTRONS PULLED STRONGLY TO ATOM

WITH HIGHER ELECTRONEGATIVITYWITH HIGHER ELECTRONEGATIVITY

POLAR BONDSPOLAR BONDSHYDROGEN IODIDE (HI)HYDROGEN IODIDE (HI)

IODINE (EN = 2.5) HAS A HIGHER IODINE (EN = 2.5) HAS A HIGHER ELECTRONEGATIVITY THAN HYDROGEN (EN = 2.1)ELECTRONEGATIVITY THAN HYDROGEN (EN = 2.1)

ELECTRONS DRAWN TOWARD IODINE NUCLEUSELECTRONS DRAWN TOWARD IODINE NUCLEUSREPRESENTED BY:REPRESENTED BY:

δδ+ + δδ--

H – IH – I or or H - IH - I

HYDROGEN DEVELOPS PARTIAL POSITIVE CHARGE, HYDROGEN DEVELOPS PARTIAL POSITIVE CHARGE, WHILE IODINE COUNTERS WITH A PARTIAL WHILE IODINE COUNTERS WITH A PARTIAL NEGATIVE CHARGENEGATIVE CHARGE


WATER AND CHLOROMETHANE ARE EXAMPLES WATER AND CHLOROMETHANE ARE EXAMPLES OF POLAR MOLECULESOF POLAR MOLECULES


TYPE OF BOND IS DETERMINED BY THE TYPE OF BOND IS DETERMINED BY THE ELECTRONEGATIVITY OF THE BONDING ELEMENTSELECTRONEGATIVITY OF THE BONDING ELEMENTS

Electronegativity Differences and Bond TypeElectronegativity Differences and Bond Type

Electronegativity Electronegativity DifferenceDifference

Type of BondType of Bond ExampleExample

0.0-0.40.0-0.4 Non-polar covalentNon-polar covalent H-H (0.0)H-H (0.0)

0.4-1.00.4-1.0 Moderately polar Moderately polar covalentcovalent

H-Cl (0.9)H-Cl (0.9)

1.0-2.01.0-2.0 Very polar Very polar covalentcovalent

H-F (1.9)H-F (1.9)

>> 2.0 2.0 IonicIonic NaNa++ClCl-- (2.1) (2.1)

POLAR MOLECULESPOLAR MOLECULES

POLAR MOLECULE HAS 1 OR MORE POLAR BONDSPOLAR MOLECULE HAS 1 OR MORE POLAR BONDS

CHARGED REGION IS A ‘POLE’CHARGED REGION IS A ‘POLE’

MOLECULE HAVING 2 POLES IS A ‘DIPOLE’MOLECULE HAVING 2 POLES IS A ‘DIPOLE’

WHEN POLAR MOLECULES ARE PLACED IN AN ELECTRIC WHEN POLAR MOLECULES ARE PLACED IN AN ELECTRIC FIELD, THEY BECOME ORIENTED WITH RESPECT TO THE FIELD, THEY BECOME ORIENTED WITH RESPECT TO THE FIELDFIELD

POLAR MOLECULESPOLAR MOLECULESIN AN ELECTRIC FIELDIN AN ELECTRIC FIELD

Neg

ati

ve P

late

Posi

tive P

late

EFFECT OF POLAR BONDS ON THE EFFECT OF POLAR BONDS ON THE MOLECULE’S POLARITY DEPENDS ON MOLECULE’S POLARITY DEPENDS ON SHAPE OF THE MOLECULE AND SHAPE OF THE MOLECULE AND POLAR BOND ORIENTATIONPOLAR BOND ORIENTATION

WATER IS A POLAR MOLECULE, BUT WATER IS A POLAR MOLECULE, BUT CARBON DIOXIDE IS NOTCARBON DIOXIDE IS NOT

POLAR MOLECULESPOLAR MOLECULES

:O

HH

:

::

::

O = C = O

BOND DISSOCIATION ENERGYBOND DISSOCIATION ENERGYENERGY NEEDED TO BREAK A ENERGY NEEDED TO BREAK A

COVALENT BONDCOVALENT BOND

INTERMOLECULAR INTERMOLECULAR ATTRACTIONSATTRACTIONS

INTERMOLECULAR FORCESINTERMOLECULAR FORCES DETERMINE COMPOUND’S PHYSICAL STATEDETERMINE COMPOUND’S PHYSICAL STATE

VERY WEAKVERY WEAK – COMPOUND IS A – COMPOUND IS A GASGASSOMEWHAT STRONGER – COMPOUND IS A SOMEWHAT STRONGER – COMPOUND IS A LIQUIDLIQUIDMUCH STRONGERMUCH STRONGER – COMPOUND IS A – COMPOUND IS A SOLIDSOLID

MOLECULAR COMPOUND MELTING AND BOILING MOLECULAR COMPOUND MELTING AND BOILING POINTS ARE LOWER THAN IONIC COMPOUNDSPOINTS ARE LOWER THAN IONIC COMPOUNDS

MOLECULAR COMPOUNDS ARE INSOLUBLE IN WATERMOLECULAR COMPOUNDS ARE INSOLUBLE IN WATERMOLECULAR COMPOUNDS DO NOT CONDUCT MOLECULAR COMPOUNDS DO NOT CONDUCT

ELECTRICITY IN THEIR LIQUID STATEELECTRICITY IN THEIR LIQUID STATE

Van der Waals FORCESVan der Waals FORCES

DISPERSION FORCESDISPERSION FORCESCAUSED BY ELECTRON MOTIONCAUSED BY ELECTRON MOTION

INCREASES AS ELECTRON NUMBER INCREASES AS ELECTRON NUMBER INCREASESINCREASES

DIPOLE INTERACTIONSDIPOLE INTERACTIONSELECTROSTATIC INTERACTION BETWEEN ELECTROSTATIC INTERACTION BETWEEN

OPPOSITE CHARGED REGIONS OF POLAR OPPOSITE CHARGED REGIONS OF POLAR MOLECULESMOLECULES

HYDROGEN BONDINGHYDROGEN BONDING

CONDITIONS FOR HYDROGEN BONDINGCONDITIONS FOR HYDROGEN BONDINGCOVALENT HYDROGEN BOND WITH HIGHLY COVALENT HYDROGEN BOND WITH HIGHLY

ELECTRONEGATIVE ELEMENTELECTRONEGATIVE ELEMENTHYDROGEN WEAKLY BONDED TO UNSHARED HYDROGEN WEAKLY BONDED TO UNSHARED

ELECTRONDS IN ANOTHER MOLECULEELECTRONDS IN ANOTHER MOLECULE

HYDROGEN BONDING OCCURS BECAUSE THERE HYDROGEN BONDING OCCURS BECAUSE THERE IS NO SHIELDING EFFECT AROUND HYDROGEN IS NO SHIELDING EFFECT AROUND HYDROGEN NUCLEUSNUCLEUS

IONIC & COVALENT COMPOUND IONIC & COVALENT COMPOUND CHARACTERISTICSCHARACTERISTICS

CharacteristicsCharacteristics Ionic CompoundsIonic Compounds Covalent CompoundsCovalent Compounds

Representative unitRepresentative unit Formula UnitFormula Unit MoleculeMolecule

Bond FormationBond Formation Transfer of one or more Transfer of one or more electrons between atomselectrons between atoms

Sharing of electron pairs Sharing of electron pairs between atomsbetween atoms

Type of elementsType of elements Metallic and non-metallicMetallic and non-metallic Non-metallicNon-metallic

Physical StatePhysical State SolidSolid Solid, liquid or gasSolid, liquid or gas

Melting PointMelting Point High (usually above 300 High (usually above 300 C)C) Low (usually below 300 Low (usually below 300 C)C)

Solubility in waterSolubility in water Usually highUsually high Usually lowUsually low

Electrical Electrical conductivity of (aq)conductivity of (aq) Good conductorGood conductor Poor to non-conductingPoor to non-conducting

COVALENT COVALENT BONDINGBONDING

THE ENDTHE END

COVALENT BONDING

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covalent bondsingles

covalent bondingchapter

number of electrons

bonding orbital2 electrons

formed2 electrons

electrons pairedparamagnetic

s electron moves

elementsh hother electrons