PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21BA+- -(Bonding)(Bonding)2pzAtomic Orbitals Atomic Orbitals of Atoms A,Bof Atoms A,Bz zA B2p 2p--++Molecular OrbitalsMolecular OrbitalsA--+ +B*(Antibonding)(Antibonding)2pzNodal Plane2pz-2pz- -++A B2p2pzz(A) + 2p(A) + 2pzz(B)(B)2p2pzz(A) - 2p(A) - 2pzz(B)(B)z Axis is taken to be line through A, Bz Axis is taken to be line through A, BzaxiszaxisBonding with 2p OrbitalsBonding with 2p OrbitalsAtomic Orbitals Atomic Orbitals of Atoms A,Bof Atoms A,BMolecular OrbitalsMolecular OrbitalsA B++--2px-2pxA B+ +- -2px2px2p(bonding)A B+-A B++--(antibonding)*2pNodal Plane2p2pxx(A) - 2p(A) - 2pxx(B)(B)2p2pxx(A) + 2p(A) + 2pxx(B)(B)zxxzNote: orbital is Note: orbital is  to bond (z) axis to bond (z) axisA,B NodalPlaneBonding with 2p Orbitals (cont)Bonding with 2p Orbitals (cont)Notational DetailNotational DetailOxtoby uses two different notations for orbitals Oxtoby uses two different notations for orbitals in the 4th and 5th editions of the class text:in the 4th and 5th editions of the class text:2px2px* i* in the 4th edition becomes g2pxg2px* in the 5th edition2px2px i in the 4th edition becomes u2pxu2px in the 5th edition2pz2pz i in the 4th edition becomes g2pzg2pz in the 5th edition2pz2pz* i* in the 4th edition becomes u2pzu2pz* in the 5th editionCORRELATION DIAGRAMCORRELATION DIAGRAM for second period diatomic moleculesE*2pz* 2p y* 2p x2px2py2pz*2pz* 2p x* 2p y2pz2px2py2p 2p2s 2s*2s2s2p 2p2s 2s*2s2s(6 Valence(6 Valenceelectronselectronsfor eachfor eachatom)atom)(3 Valence(3 Valenceelectrons electrons for each for each atom)atom)BB22Z ≤ 7Z ≤ 7OO22Z ≥ 8Z ≥ 8Molecular OrbitalsMolecular OrbitalsMolecular OrbitalsMolecular OrbitalsNote unpairedNote unpairedelectronselectronsNote order offilling 2pzDegenerateDegenerate orbitalsorbitalsMolecular Orbitals of Homonuclear Diatomic Molecules(Å)HeHe22LiLi22BeBe22BB22CC22NN22OO22FF22NeNe2224246810121416101012332100.740.7452522.672.672.452.451.591.591.241.241.101.101.211.211.411.41--431.0000081059289599942942494154-Valence Electron Configuration# Valence# ValenceElectronsElectronsBond LengthBond OrderBond Bond EnergyEnergy(kJ/mole)(kJ/mole)Mole-Mole-culeculeHH22((2s2s))22((2s2s*)*)22((2p2pzz))22((2p2p))44((2p2p*)*)44((2s2s))22((2s2s*)*)22((2p2pzz))22((2p2p))44((2p2p*)*)22((2s2s))22((2s2s*)*)22((2p2p))4 4 ((2p2pzz))22((2s2s))22((2s2s*)*)22((2p2p))44((2s2s))22((2s2s*)*)22((2p2p))22((2s2s))22((2s2s*)*)22((2s2s))22((1s1s))22((1s1s*)*)22((1s1s))22((2s2s))22((2s2s*)*)22((2p2pzz))22((2p2p))44((2p2p*)*)44((2p2pzz*)*)22  Bonding in Polyatomic MoleculesBonding in Polyatomic MoleculesBasically two ways to approach polyatomics.Basically two ways to approach polyatomics.First is to use First is to use delocalized M.O.’sdelocalized M.O.’s where where ee -- are not confined to a are not confined to a single bond (region between 2 atoms) but can wander over 3 or single bond (region between 2 atoms) but can wander over 3 or more atoms. We will use this approach later for C bonding.more atoms. We will use this approach later for C bonding.Second is to use Second is to use hybridization of atomic orbitalshybridization of atomic orbitals and then use these and then use theseto form localized (usually) bonds.to form localized (usually) bonds.Localized BeHLocalized BeH22 orbitals: orbitals:++BeBe++++++spsp+ + spsp- - Add spAdd sp++ + 1s + 1sto get localizedto get localizedBe-H bondBe-H bond}Add spAdd sp-- + 1s + 1sto get localizedto get localizedBe-H bondBe-H bond}HHHH........––––++++H 1s + (spH 1s + (sp-- ))H 1s + (spH 1s + (sp++ ))BeBeHHHHBeBeandand++....++....––––BHBH33 Fragment: Fragment:spsp22hybridhybrid--++120˚120˚Boron NucleusBoron NucleusSecond spSecond sp22 points points along this directionalong this directionThird spThird sp22points alongpoints alongthis directionthis direction•33 sp sp22hybridshybrids120˚120˚Overlap with H 1s to give 3 B-H bonds Overlap with H 1s to give 3 B-H bonds in a planein a plane pointing pointing at at 120º120º with respect to each other: BH with respect to each other: BH33BBNote B has 3 Note B has 3 valence electronsvalence electrons1s1s222s2s222p2p++++++++HH++HH++HH120˚2s + 2p2s + 2pxx + 2p + 2pyy + 2p + 2pzz  sp sp33 gives gives 4 hybrid orbitals4 hybrid orbitals which point to which point to the corners of a tetrahedron. Angle between is the corners of a tetrahedron. Angle between is 109º28’109º28’ spsp33 [1/4 s, 3/4 p]. Tetrahedral hybrids. [1/4 s, 3/4 p]. Tetrahedral hybrids.4 H atoms have 4 x 1s 4 H atoms have 4 x 1s  4 valence 4 valence e e -- EE2s2s222p2p1s1s22spsp33spsp33spsp33spsp331s1s22Geometry of carbon spGeometry of carbon sp33/H 1s Bonds in methane (CH/H 1s Bonds in methane (CH44):):spsp33 hybridization on C leads to 4 bonds. CH hybridization on C leads to 4 bonds. CH44 is a is a good example.good example.CCHHHHHHHHSummary of Hybridization ResultsSummary of Hybridization ResultsBeHBeH2222 sp splinear H-Be-Hlinear H-Be-HBHBH3333 sp sp22trig. plane trig. plane (120º H-B-H (120º H-B-H angle)angle)CHCH4444 sp sp33tetrahedral tetrahedral (109º28’ (109º28’ H-C-H angles)H-C-H angles)ExampleExampleGroups Attached Groups Attached Hybrid HybridGeometryGeometryto Center Atomto Center Atom2pz2py2px1s1s1sLocalized Bonds and Lone Pair ElectronsLocalized Bonds and Lone Pair ElectronsNH3This predicts 90º geometry3H, 1s (no choice) N: 1s22s22p3NitrogenNitrogennucleusnucleusH atom 1sorbitalN107˚HHHGeometry of NHGeometry of NH33 found to be Trigonal Pyramidal found to be Trigonal Pyramidal4 N sp4 N sp33 orbitals combine with 3 1s H orbitals to give 3 sp orbitals combine with 3 1s H orbitals to give 3 sp33, 1s M.O.’s, 1s M.O.’sleaving one spleaving one sp33 hybrid left hybrid leftOf 5 valence Of 5 valence e e -- in N, 2 go into one sp in N, 2 go into one sp33 orbital, 3 go into other 3 sp orbital, 3 go into other 3 sp33,s.,s.(combined with H (1s))(combined with H (1s))One of the driving