IB Chemistry on Valence Bond and Hybridization Theory
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IB Chemistry on Valence Bond and Hybridization Theory
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IB Chemistry on Valence Bond and Hybridization Theory
- 1. Tutorial on Valence Bond Theory and Hybridization. Prepared by Lawrence Kok http://lawrencekok.blogspot.com
- 2. brown liquid . : : : x x Click here simulation on covalent bond yellow gas greenish gas violet solid Covalent Bonding Covalent bonding between non metals 2.8.7 Gp 17 Non metal achieve stable octet structure Covalent Bonding Electrostatic forces attraction between nucleus with shared pair electron CI shared pair electron 2.8.8 2.8.7 Sharing electron Gp 17 Non metal 2.8.8 CI Non metal •High EN value •Gain electron (anion) •Electronegative ions CI CI Lewis structure/diagram . Electron cross dot . Valence/bonding pair electron : : CI CI : xx x x X x x xx CI CI x x CI CI Non metal •High EN value •Gain electron (anion) •Electronegative ions Single covalent bond – shared pair electron
- 3. Bond Bond : . C I. B - 6 valence e : : . x order Bond strength Bond length/pm C - C 1 347 154 C = C 2 612 134 C Ξ C 3 820 120 N - N 1 159 145 N = N 2 418 123 N Ξ N 3 914 110 Bond length and Bond strength Bond length = 0.199nm Lewis structure/diagram . Electron cross dot . Valence/bonding pair electron : : x x : : : CI CI xx . Electron cross dot . Valence/bonding pair electron . Electron cross dot . Valence/bonding pair electron . : : :N N: N N : . x x X X xx CI CI Lewis structure/diagram O x x x x xx CI CI :O : xx O : x x x x x O : : x x x N O O Lewis structure/diagram : N O : Triple bond > Double bond > Single bond Bonding pair e -involve in bonding Bond length decrease Bond strength Increase (Double/Triple bond) Bond length = 0.121nm Bond length = 0.110nm Bond order up – Bond strength up – Bond length down : O Non bonding pair (Lone pair electron) Bonding pair electron Dative bond (electron pair of oxy) :C O: Bonding pair electron Types of bonding Lone pair e –not involve in bonding Dative/coordinate bond - pair e come from an atom Exception to octet rule All period 2 element - observe octet rule except Be and B Electron deficient Less than 8 valence e All period 3 element - observe octet rule except P and S Expanded octet More than 8 valence e : : : : :CI .x Be CI: x x. Be - 4 valence e : : x : : : CI B CI : CI P S CI CI CI CI CI CI CI CI CI CI P - 10 valence e S – 12 valence e : :
- 4. Valence Shell Electron Pair Repulsion Predict molecular shape/geometry Shape determine by electron pairs/ electron charge centers/ECC Bonding/lone pair – repel each other Bonding/lone pair arrange themselves as far as possible (minimise repulsion) Valence Shell Electron Pair Repulsion NOT surrounding atoms .. N H H H Principles of VSEPR Shape of molecule 1 Determine number valence e around central atom 2 Single, double, triple bond , lone pair act as electron charge center/ECC 3 4 Lone pair-lone pair > Lone pair-bonding pair > bonding pair-bonding pair repulsion 5 6 ECC or electron pair position in equatorial first, then axial Lewis structure .. N H H VSEPR H Shape Excellent VSEPR simulation Click here ✓ Click here VSEPR simulation Click here VSEPR notes
- 5. 1 lone pair 4 ECC N – central atom .. Valence Shell Electron Pair Repulsion Principles of VSEPR Determine number 1 valence e around central atom 2 Single, double, triple bond , lone pair act as electron charge center/ECC 3 Bonding/lone pair repel each other Lone /lone pair > Lone /bond pair > bond/bond pair repulsion Bonding/lone pair arrange themselves as far as possible (minimise repulsion) 4 5 For 5/6 ECC: ECC position in equatorial first, then axial .. N H H H 3 bonding pair C H H C N 3 ECC H =O 2 ECC H O H .. 4 ECC 2 lone pair 1 lone pair 0 lone pair > > Repulsion greater Repulsion greater Repulsion greater - Bond angle smaller ✓ ECC far apart – Bond angle greatest – minimise repulsion 6 Lone pair need more space Multiple bonds more space Equal repulsion Unequal repulsion 90° 120° 109.5° 107° 180°
- 6. Valence Shell Electron Pair Repulsion Predict molecular shape/geometry Shape determine by electron pairs/ electron charge centers/ECC Bonding/lone pair – repel each other Bonding/lone pair arrange themselves as far as possible (minimise repulsion) Valence Shell Electron Pair Repulsion .. N H H H Principles of VSEPR Shape of molecule 1 Determine number valence e around central atom 2 Single, double, triple bond , lone pair act as electron charge center/ECC 3 4 Lone pair-lone pair > Lone pair-bonding pair > bonding pair-bonding pair repulsion 5 6 ECC or electron pair position in equatorial first, then axial Lewis structure .. N H H H VSEPR Geometry 4 ECC 3 bonding pair 1 lone pair Trigonal pyrimidal 1 2 3 Bond pair electron •Occupy smaller region space bet nuclei •Repulsion less Lone pair electron nucleus > Bonding pair electron nuclei Lone pair electron •Electron pair occupy greater space •Repel any bonding pair nearby •Lone pair repulsion > bonding pair repulsion Double bond •Repulsion greater •Angle smaller, 111.4° B F 120° F F 120° 120° Single bond •Equal repulsion •Angle 120° space occupy by electron space occupy by electron
- 7. Valence Shell Electron Pair Repulsion .. N H H H Shape of molecule - Lewis structure - Valence electron involve in bonding - Localized region space - Sharing of valence electron .. N H H H Geometry 4 ECC 3 bonding pair 1 lone pair Trigonal pyrimidal 1 2 3 Using VSEPR predict shape - Atomic orbital overlap - Electron localized in overlap region -Electron density between nuclei Quantum mechanics approach 1s orbital 1s orbital 1s orbital 2p orbital 2p orbital 2p orbital Localized electron pair 1s 1s Electron density/cloud Too near repulsion bet +ve nuclei Attraction bet nuclei with electron cloud Minimum energy, most stable, bond length
- 8. Atomic Orbitals n= 2 n= 1 l=2 l=1 l=0 3d sublevel 3p sublevel 2p sublevel 2s sublevel l=0 1s sublevel n= 3 l=1 l=0 3s sublevel ml =+2 ml =+1 ml = 0 ml =-1 ml =-2 ml =+1 ml = 0 ml =-1 ml = 0 ml =+1 ml = 0 ml =-1 ml =0 ml =0 3dx 2 – y 3dyz orbital 3dz 2 orbital 3dxz orbital 3dxy orbital 3py orbital 3pz orbital 3px orbital 3s orbital 2py orbital 2pz orbital 2px orbital 2s orbital 1s orbital 2orbital Click here to view simulation Energy Level Atomic orbital overlap Electron localized in overlap region Electron density bet nuclei 1s orbital 1s orbital 1s orbital 2p orbital 2p orbital 2p orbital Localized electron pair Click here hybridization notes Click here orbital overlap
- 9. Sigma σ bond •2 atomic orbital overlap •End to end overlap along internuclear axis •Overlap of orbitals between nuclei •Constructive interference overlap Molecular orbital sigma bond Pi π bond •2 p orbital overlap sideways •Overlap of unhybridized/parallel p orbital •Parallel p orbital overlaps •Sideway interaction of 2 p orbitals + Atomic orbital overlap + overlap Atomic orbital overlap + + Molecular orbital pi bond
- 10. Sigma σ bond •2 atomic orbital overlap •End to end overlap along internuclear axis •Overlap of orbitals between nuclei •Constructive interference sigma bond overlap Molecular orbital sigma bond Pi π bond •2 p orbital overlap sideways •Overlap of unhybridized/parallel p orbital •Parallel p orbital overlaps •Sideway interaction of 2 p orbitals + Atomic orbital overlap + overlap internuclear axis Atomic orbital overlap + + Molecular orbital pi bond + Sigma bond stronger- greater orbital overlap Pi bond weaker - less orbital overlap
- 11. Formula Lewis Structure VSEPR Hybridization NH3 1 2 3 4 H H H
- 12. Mixing of atomic orbital to form new hybrid orbital for bonding Atomic orbital + Atomic orbital → Hybrid orbital One s orbital + One p orbital TWO → sp hybrid orbital + 50% s character 50% p character One s orbital + Two p orbital → THREE sp2 hybrid orbital + + 33% s character 66% p character One s orbital + Three p orbital → FOUR sp3 hybrid orbital + + + Formula Lewis Structure VSEPR Hybridization NH3 1 2 3 4 H H H 1 2 3 4 25% s character 75% p character
- 13. Mixing of atomic orbital to form new hybrid orbital for bonding Atomic orbital + Atomic orbital → Hybrid orbital One s orbital + One p orbital TWO → sp hybrid orbital + 50% s character 50% p character One s orbital + Two p orbital → THREE sp2 hybrid orbital + + 33% s character 66% p character One s orbital + Three p orbital → FOUR sp3 hybrid orbital + + + Formula Lewis Structure VSEPR Hybridization NH3 1 2 3 4 H H H VSEPR Electron Domain Electron charge center Hybridization 2 sp 3 sp2 4 sp3 5 dsp3 6 d2sp3 1 2 3 4 Atomic orbital Type of Hybridization Number Hybrid orbitals VSEPR Number Electron domain VSEPR Electron geometry domain s,p sp 2 2 Linear s,p,p sp2 3 3 Trigonal planar s,p,p,p sp3 4 4 Tetrahedral s,p,p,p,d dsp3 5 5 Trigonal Bipyrimidal s,p,p,p,d,d d2sp3 6 6 Octahedral 25% s character 75% p character Excellent simulation✓ Click here for simulation
- 14. Valence Shell Electron Pair Repulsion .. N H H H Shape of molecule .. N H H H Geometry 4 ECC 3 bonding pair 1 lone pair Trigonal pyrimidal 1 2 3 - Lewis structure - Valence electron involve in bonding - Localized region space - Sharing of valence electron Using VSEPR predict shape
- 15. Valence Shell Electron Pair Repulsion .. N H H H Shape of molecule - Lewis structure - Valence electron involve in bonding - Localized region space - Sharing of valence electron .. N H H H Geometry 4 ECC 3 bonding pair 1 lone pair Trigonal pyrimidal 1 2 3 - Atomic orbital overlap - Electron localized in overlap region -Electron density between nuclei Using VSEPR predict shape - Quantum mechanics approach - Strength covalent bond proportional to overlap bet orbitals - Greater overlap – stronger bond - Atom undergo hybridization to maximize overlap - Wave combine constructive/destructively form hybrid orbital 1s orbital 1s orbital 1s orbital 2p orbital 2p orbital 2p orbital Localized electron pair Orbital - Probability of finding electron in a region space - Cloud of probability - Not possible determine exact location electron - Electron density Electron cloud
- 16. sp hybridization, Beryllium hydride, BeH2 sp sp 1s 1s 2s s orbital p orbital 2p 4Be - 1s2 2s2 1s 2p High energy excited Ground state Excited state 2py 2pz Hybridized state 2s sp hybridization + sp hybrid orbital + + Be H – Be - H Be – sp hybridization - TWO sp hybrid orbitals - Linear electron distribution - 2 bonding pair - sp orbital Be overlap with s orbital hydrogen
- 17. sp hybridization, Beryllium hydride, BeH2 sp sp 1s 1s 2s s orbital p orbital 2p 4Be - 1s2 2s2 1s 2p High energy excited Ground state Excited state 2py 2pz Hybridized state 2s sp hybridization + sp hybrid orbital + + Be H – Be - H sp2 hybridization Boron hydride, BH3 High energy 2s 1s 5B - 1s2 2s3 Ground state 2p + + 1s 2s 2p 1s 2p excited sp2 hybridization sp2 sp2 sp2 B Excited state Hybridized state Be – sp hybridization B - TWO sp hybrid orbitals - Linear electron distribution - 2 bonding pair - sp orbital Be overlap with s orbital hydrogen H B – sp2 hybridization - THREE sp2 hybrid orbitals - Trigonal electron distribution - 3 bonding pair - sp2 orbital B overlap with s orbital hydrogen B H H
- 18. sp3 hybridization methane, CH4 1s 1s 2s 2p 6C - 1s2 2s22p2 1s 2p excited Ground state Excited state Hybridized state 2s sp3 hybridization + sp3 sp3 sp3 sp3 C + - Four sp3 hybrid orbitals - Tetrahedral electron distribution - 4 bonding pair - sp3 orbital carbon overlap with s orbital hydrogen CH4
- 19. sp3 hybridization methane, CH4 sp3 sp3 sp3 sp3 1s 1s 2s 2p 6C - 1s2 2s22p2 1s 2p excited Ground state Excited state Hybridized state 2s sp3 hybridization + sp3 hybridization ammonia NH3 2s 1s Ground state 2p 1s 2s 2p 1s excited + sp3 hybridization sp3 sp3 sp3 Excited state Hybridized state C + - Four sp3 hybrid orbitals - Tetrahedral electron distribution - 4 bonding pair - sp3 orbital carbon overlap with s orbital hydrogen 7N - 1s2 2s22p3 sp3 + NH3 - Four sp3 hybrid orbitals - Tetrahedral electron distribution - 3 Bonding pair/1 lone pair - sp3 orbital nitrogen overlap with s orbital hydrogen CH4
- 20. sp2 hybridization ethene, C2H4 1s 1s 2s 2p 6C - 1s2 2s22p4 1s 2p excited Ground state Excited state Hybridized state 2s sp2 hybridization + sp2 sp2 sp2 unhybridized 2p orbital C2H4 unhybridized 2p orbital overlap form π bond C
- 21. sp2 hybridization ethene, C2H4 2p excited 2s 1s 2p 1s 1s 2s 2p 6C - 1s2 2s22p4 1s 2p Ground state Excited state C Hybridized state 2s sp2 hybridization + sp2 sp2 sp2 unhybridized 2p orbital C2H4 sp hybridization ethyne, C2H2 1s 2s 6C - 1s2 2s22p4 Ground state sp hybridization + unhybridized 2p orbital C sp sp unhybridized 2p orbital overlap form π bond unhybridized 2p orbital overlap form π bond π bond Video on hybridization Click here to view hybridization Click here hybridization theory
- 22. sp2 hybridization methanal, H2CO 1s 1s 2s 2p 6C - 1s2 2s22p4 1s 2p excited Ground state Excited state Hybridized state 2s sp2 hybridization + sp2 sp2 sp2 unhybridized 2p orbital C unhybridized 2p orbital overlap form π bond C Oxygen sp2 hybridization
- 23. sp2 hybridization methanal, H2CO 2p excited 2s 1s 2p 1s 1s 2s 2p 6C - 1s2 2s22p4 1s 2p Ground state Excited state Hybridized state 2s sp2 hybridization + sp2 sp2 sp2 unhybridized 2p orbital 1s 2s 6C - 1s2 2s22p4 Ground state sp hybridization + unhybridized 2p orbital sp sp C unhybridized 2p orbital overlap form π bond unhybridized 2p orbital carbon overlap form π bond sp hybridization carbon dioxide, CO2 C sp hybridization C sp2 hybridization O C Oxygen sp2 hybridization
- 24. sp3 hybridization water H2O 1s 1s 2s 2p 8O - 1s2 2s22p4 1s 2p excited 2s sp3 hybridization + sp3 sp3 sp3 sp3 O + - Four sp3 hybrid orbitals - Tetrahedral electron distribution - 2 bonding pair/ 2 lone pair - sp3 orbital oxygen overlap with s orbital hydrogen H2O : : O H H
- 25. sp3 hybridization water H2O sp3 sp3 sp3 sp3 1s 1s 2s 2p 8O - 1s2 2s22p4 1s 2p excited 2s sp3 hybridization + sp3 hybridization phosphorus trichloride PCI3 2s Ground state 1s 2p 1s 2s 2p 1s excited + sp3 sp3 sp3 Excited state Hybridized state O + - Four sp3 hybrid orbitals - Tetrahedral electron distribution - 2 bonding pair/ 2 lone pair - sp3 orbital oxygen overlap with s orbital hydrogen 15P - 1s2 2s22p63s23p3 sp3 + : : H H PCI3 - Four sp3 hybrid orbitals - Tetrahedral electron distribution - 3 bonding pair/1 lone pair - sp3 orbital phosphorus overlap with p orbital chlorine H2O 3s 3p 3s 3p 2s 2p sp3 hybridization CI 3p O P P : P CI CI CI
- 26. hybridization sp3 2p excited 2s sp3 sp3 sp3 sp3 1s CI 1s 1s PCI3 P CI CI 2s 2p 3s 3p 3s 3p 2s 2p CI 3p + - Four sp3 hybrid orbitals - Tetrahedral electron distribution - 3 bonding pair/1 lone pair - sp3 orbital phosphorus overlap with p orbital chlorine P Phosphorus exist as PCI3 or PCI5 sp3 hybridization phosphorus trichloride PCI3 :
- 27. hybridization 2p excited 2s sp3 sp3 sp3 sp3 1s CI 1s 1s sp3 dsp3 hybridization phosphorus pentachloride PCI5 2s Ground state 1s 2p 1s 2s 2p 1s excited Excited state Hybridized state 15P - 1s2 2s22p63s23p3 PCI3 - Five dsp3 hybrid orbitals - Trigonal bipyrimidal electron distribution - 5 Bonding pair - dsp3 orbital phosphorus overlap with p orbital chlorine 3s 3p 3s 3p 2s 2p dsp3 hybridization CI 3p P P CI CI 2s 2p 3s 3p 3s 3p 2s 2p CI 3p + - Four sp3 hybrid orbitals - Tetrahedral electron distribution - 3 bonding pair/1 lone pair - sp3 orbital phosphorus overlap with p orbital chlorine P 3d 3d 5 dsp3 + Phosphorus exist as PCI3 or PCI5 sp3 hybridization phosphorus trichloride PCI3 ✓ Expanded Octet P Click here to view :
- 28. 2p excited 2s sp3 hybridization 1s 1s sp3 SF2 S F F 1s 2s 2p 3s 3p 3s 3p 2s sp3 sp3 sp3 2p F 3p + - Four sp3 hybrid orbitals - Tetrahedral electron distribution - 2 bonding pair/2 lone pair - sp3 orbital sulfur overlap with p orbital fluorine S Sulfur exist as SF2, SF4 or SF6 sp3 hybridization SF2 ::
- 29. 2p excited 2s sp3 hybridization 1s 1s sp3 dsp3 hybridization SF4 2s Ground state 1s 2p 1s 2s 2p 1s excited sp3 sp3 sp3 Excited state Hybridized state 15S - 1s2 2s22p63s23p6 SF2 S :: - Five dsp3 hybrid orbitals - Trigonal bipyrimidal electron distribution - 4 bonding pair/1 lone pair - dsp3 orbital sulfur overlap with p orbital fluorine 3s 3p 3s 3p 2s 2p dsp3 hybridization F 3p S S F F 1s 2s 2p 3s 3p 3s 3p 2s 2p F 3p + - Four sp3 hybrid orbitals - Tetrahedral electron distribution - 2 bonding pair/2 lone pair - sp3 orbital sulfur overlap with p orbital fluorine S 3d 3d 5 dsp3 + Sulfur exist as SF2, SF4 or SF6 sp3 hybridization SF2 Expanded Octet F F F F SF4 S ✓
- 30. 2p excited 2s sp3 hybridization 1s 1s sp3 SF2 1s 2s 2p 3s 3p 3s 3p 2s sp3 sp3 sp3 2p F 3p + - Four sp3 hybrid orbitals - Tetrahedral electron distribution - 2 Bonding pair/2 lone pair - sp3 orbital sulfur overlap with p orbital fluorine S Sulfur exist as SF2, SF4 or SF6 sp3 hybridization SF2 F F :S:
- 31. 2p excited 2s sp3 hybridization 1s 1s sp3 sp3 sp3 sp3 d2sp3 hybridization SF6 2s Ground state 1s 2p 1s 2s 2p 1s excited Excited state Hybridized state 15S - 1s2 2s22p63s23p6 SF2 - Six d2sp3 hybrid orbitals - Octahedral electron distribution - 6 Bonding pair - d2sp3 orbital sulfur overlap with p orbital fluorine 3s 3p 3s 3p 2s 2p d2sp3 hybridization F 3p S 1s 2s 2p 3s 3p 3s 3p 2s 2p F 3p + - Four sp3 hybrid orbitals - Tetrahedral electron distribution - 2 Bonding pair/2 lone pair - sp3 orbital sulfur overlap with p orbital fluorine S 3d 3d 6 d2sp3 + Sulfur exist as SF2, SF4 or SF6 sp3 hybridization SF2 Expanded Octet SF6 3d F F :S: S ✓
- 32. IB Question State the type of hybridization shaded in red CO2 SO3 SO2 NH3 CH H2O H2CO 3COOH CH4 CO2- 3 NO2 XeF2 CIF3 - BrF5 XeF4 : State the hybridization shaded in red and number of sigma and pi bonds sigma bonds pi bond : : C : : : C :
- 33. IB Question State the type of hybridization shaded in red CO2 SO3 SO2 NH3 CH H2O H2CO 3COOH sp2 sp2 sp3 sp2 sp3 sp2 CH4 CO2- 3 NO2 XeF2 CIF3 - BrF5 XeF4 sp : sp2 sp2 d2sp3 dsp3 dsp3 d2sp3 sp3 State the hybridization shaded in red and number of sigma and pi bonds sigma bonds pi bond : C- sp2 N- sp3 C- sp2 C- sp2 : C : : : C : N- sp3 N- sp3 C - sp3 19 sigma bonds 2 pi bonds 12 sigma bonds 2 pi bonds 5 sigma bonds 1 pi bond C- sp3 C- sp2
- 34. ECC Bonding Pair Lone Pair Electron Distribution Electron geometry domain Hybridization s, p VSEPR Atomic orbitals Type of Hybridization sp Number of Hybrid orbitals s, p, p s, p, p, p s, p, p, p, d s, p, p, p, d, d sp2 sp3 dsp3 d2sp3 linear Trigonal planar Tetrahedral Trigonal Bipyrimidal Octahedral Shape/Geometry linear s, p, p sp2 Trigonal planar Tetrahedral Tetrahedral s, p, p, p s, p, p, p sp3 sp3 : .. Trigonal Bipyrimidal s, p, p, p, d dsp3 Trigonal Bipyrimidal s, p, p, p, d dsp3 Trigonal Bipyrimidal s, p, p, p, d dsp3 .... Octahedral Octahedral s, p, p, p, d, d s, p, p, p, d, d d2sp3 d2sp3 .. .... ...... .... .. Trigonal planar Bend V shape Tetrahedral Trigonal pyrimidal Bend V shape Trigonal Bipyrimidal Seesaw T shape Linear Octahedral Square pyrimidal Square planar
- 35. Acknowledgements Thanks to source of pictures and video used in this presentation Thanks to Creative Commons for excellent contribution on licenses http://creativecommons.org/licenses/ Prepared by Lawrence Kok Check out more video tutorials from my site and hope you enjoy this tutorial http://lawrencekok.blogspot.com