Covalent BondingCovalent Bonding

Covalent Bonding and Covalent Bonding and Covalent NomenclatureCovalent Nomenclature

Covalent bonding – sharing of electrons

Made of two or more nonmetals!

Formed between two nonmetals Formed between two nonmetals Electrons are shared by the atomsElectrons are shared by the atoms

Covalent Bonds

Covalent BondsCovalent Bonds

In a covalent bond, the shared In a covalent bond, the shared electrons are considered part of the electrons are considered part of the complete outer energy level of both complete outer energy level of both atoms involved.atoms involved.

Covalent bonding generally occurs Covalent bonding generally occurs when elements are relatively close to when elements are relatively close to each other on the Periodic Table.each other on the Periodic Table.

When two or more atoms bond When two or more atoms bond covalently, a covalently, a moleculemolecule is formed. is formed.

single bondsingle bond shares one pair of shares one pair of electronselectrons

double bonddouble bond shares two pairs of shares two pairs of electronselectrons

triple bondtriple bond shares three pairs shares three pairs

of electronsof electrons

Covalent Bond SharingCovalent Bond Sharing

Covalent compound formulasCovalent compound formulas

Examples: carbon dioxide, Examples: carbon dioxide, carbon tetrachloridecarbon tetrachloride

Oxidation Number: Unpaired Oxidation Number: Unpaired Valence ElectronsValence Electrons– Number of covalent Number of covalent

bonds an atom can formbonds an atom can form– Hydrogen = 1Hydrogen = 1– Oxygen = 2; single and Oxygen = 2; single and

double bondsdouble bonds– Nitrogen = 3; single, Nitrogen = 3; single,

double and triple bondsdouble and triple bonds– Carbon = 4 - single, Carbon = 4 - single,

double and triple bondsdouble and triple bonds

Lewis Dot StructuresLewis Dot StructuresHydrogen chloride Hydrogen chloride

formationformation

Lewis Dot StructuresLewis Dot StructuresPhosphorus tribromide (PBrPhosphorus tribromide (PBr33) formation ) formation

Properties of Covalent MoleculesProperties of Covalent Molecules

Solids, liquids, or gases at room Solids, liquids, or gases at room temperaturetemperature

Nonconductive as solidsNonconductive as solids May dissolve in waterMay dissolve in water Dissolve in nonpolar solvents Dissolve in nonpolar solvents

(hexane or alcohol)(hexane or alcohol) Non-conductive when dissolvedNon-conductive when dissolved Low melting pointsLow melting points

Learning CheckLearning Check

Indicate whether a bond between the Indicate whether a bond between the following would be following would be 1) Ionic1) Ionic 2) covalent2) covalent

________ A. sodium and oxygenA. sodium and oxygen

________ B. nitrogen and oxygenB. nitrogen and oxygen

________C. phosphorus and chlorineC. phosphorus and chlorine

________ D. calcium and sulfurD. calcium and sulfur

________E. chlorine and bromineE. chlorine and bromine

Polar covalent bondsPolar covalent bonds

Electrons are unequally sharedElectrons are unequally shared. . The molecule has an area of The molecule has an area of

positive charge and an area of positive charge and an area of negative charge.negative charge.

Not symmetricalNot symmetricalExamples: Examples: HH22O(water) and O(water) and

NHNH33(ammonia)(ammonia)

Electrons are equally shared Electrons are equally shared and there is no charge.and there is no charge.

SymmetricalSymmetrical Examples: COExamples: CO22(carbon (carbon

dioxide), CCldioxide), CCl44(carbon (carbon tetrachloride), Otetrachloride), O22(oxygen (oxygen gas)gas)

Nonpolar covalent bonds

Learning CheckLearning Check

Identify the type of bond between the Identify the type of bond between the following atoms following atoms A. K-NA. K-N

1) nonpolar 1) nonpolar 2) polar2) polar 3) ionic3) ionicB. N-OB. N-O

1) nonpolar1) nonpolar 2) polar2) polar 3) ionic3) ionicC. Cl-ClC. Cl-Cl

1) nonpolar 2) polar1) nonpolar 2) polar 3) 3) ionicionic

Naming Binary Naming Binary Molecular CompoundsMolecular Compounds

Two nonmetalsTwo nonmetalsName each element Name each element End the last element in -ideEnd the last element in -ideAdd prefixes to show more than 1 Add prefixes to show more than 1

atomatomFor example: Carbon dioxide COFor example: Carbon dioxide CO22

Prefixes for namingPrefixes for naming

*Mono *Mono 11 * Penta * Penta55

*Di*Di 22 * Hexa* Hexa 66

*Tri*Tri 33 * Hepta* Hepta 77

*Tetra*Tetra 4 4 * Octa* Octa 88

Used to indicate multiplesUsed to indicate multiples Mono normally omittedMono normally omitted

– Exception: carbon monoxideException: carbon monoxide

Learning CheckLearning Check

Fill in the blanks to complete the Fill in the blanks to complete the following names of covalent following names of covalent compounds.compounds.

CO CO carbon ______oxidecarbon ______oxide

COCO22 carbon _______________carbon _______________

PClPCl33 phosphorus _______chloridephosphorus _______chloride

CClCCl44 carbon ________chloridecarbon ________chloride

NN22OO _____nitrogen _____oxide_____nitrogen _____oxide

Learning CheckLearning Check

A.A. PP22OO55 1) phosphorus oxide1) phosphorus oxide2) phosphorus pentoxide2) phosphorus pentoxide3) diphosphorus pentoxide3) diphosphorus pentoxide

B.B. ClCl22OO77 1) dichlorine heptoxide1) dichlorine heptoxide2) dichlorine oxide2) dichlorine oxide3) chlorine heptoxide3) chlorine heptoxide

VSEPR TheoryVSEPR TheoryValence Shell Electron Pair Valence Shell Electron Pair

RepulsionRepulsion

VSEPR TheoryVSEPR Theory

Predicts the molecular shape of a Predicts the molecular shape of a bonded moleculebonded molecule

Electrons around the central atom Electrons around the central atom arrange themselves as far apart from arrange themselves as far apart from each other as possibleeach other as possible

Unshared pairs of electrons (lone Unshared pairs of electrons (lone pairs) on the central atom repel the pairs) on the central atom repel the mostmost

So only look at what is connected to So only look at what is connected to the central atomthe central atom

LinearLinear

2 atoms attached to center atom2 atoms attached to center atom 0 lone pairs0 lone pairs

Bond angle = 180Bond angle = 180oo

Ex. : BeFEx. : BeF22

Trigonal PlanarTrigonal Planar

3 atoms attached to center atom3 atoms attached to center atom 0 lone pairs0 lone pairs

Bond angle = 120Bond angle = 120oo

Ex. : AlFEx. : AlF33

Tetrahedral Tetrahedral

4 atoms attached to center atom4 atoms attached to center atom 0 lone pairs0 lone pairs

Bond angle = 109.5Bond angle = 109.5oo

Ex. : CHEx. : CH44

BentBent

2 atoms attached to center atom2 atoms attached to center atom 2 lone pairs2 lone pairs

Bond angle = 104.5Bond angle = 104.5oo

Ex. : HEx. : H22OO

Metallic BondingMetallic Bonding

Nature of Metallic BondingNature of Metallic Bonding Metal atoms from latticesMetal atoms from lattices The outer valence shell electrons of The outer valence shell electrons of

each metal atom contribute to a each metal atom contribute to a “sea” of electrons in the lattice“sea” of electrons in the lattice

Metallic PropertiesMetallic Properties High thermal and electrical conductivityHigh thermal and electrical conductivity Malleable- can be hammered into Malleable- can be hammered into

sheetssheets Ductile- can be drawn into wireDuctile- can be drawn into wire