09-04 - How How has quantum mechanics increased our...

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Unformatted text preview: 9/8/2009 How How has quantum mechanics increased our understanding of molecules; their bonding and how they they react? How How has quantum mechanics increased our understanding of molecules; their bonding and how they they react? quantum mechanics quantum mechanics x y atomic 2s orbital + higher energy d and f atomic orbitals 3 atomic 2p orbitals H· atomic 1s orbital H· Z 1 2 Atomic Atomic s, p orbitals and their hybrids. How are the orbitals arranged about a sp hybridized atom? x y Z 1 s orbital 3 p orbitals 3 2 sp hybrid sp orbitals orbitals pz pz + py atomic orbitals orbitals 4 Why are hybrid rather than atomic orbitals more useful in molecular bonding? How are the orbitals arranged about a sp hybridized atom? 2 sp hybrid sp orbitals orbitals pz pz + py atomic orbitals orbitals 5 2 sp hybrid sp orbitals orbitals pz pz + py atomic orbitals orbitals 6 1 9/8/2009 How are the orbitals arranged about a sp hybridized atom? Consider Consider the combination of one s atomic orbital and two two p atomic orbitals. s px py sp sp hybridized atom atom 2 sp hybrid sp orbitals orbitals pz pz + py atomic orbitals orbitals y z x pz 7 8 How many sp2 hybrid orbitals will result from the combination hybrid of of one s atomic orbital and two p atomic orbitals? A. 1 B. 2 C. 3 How many sp2 hybrid orbitals will result from the combination hybrid of of one s atomic orbital and two p atomic orbitals? A. 1 B. 2 C. 3 x y z y z x How will these 3 sp2 hybrid orbitals be hybrid arranged arranged in space? pz 9 pz A. A. xy plane B. xz plane B. C. yz plane C. 10 How are the hybrid orbitals arranged about a sp2 hybridized hybridized atom? atom? How many hybrid orbitals are on an sp3 hybridized atom? s px py z y z x y interorbital angle = 120° 120° x an sp2 hybridized atom hybridized pz 11 pz 12 2 9/8/2009 How many hybrid orbitals are on an sp3 hybridized atom? Summary sp sp2 sp3 interorbital angle = 109.5° 109.5° x y z hybrid hybrid orbitals orbitals an sp3 hybridized hybridized atom atomic atomic orbitals orbitals 13 14 Summary sp 180 Why Why are hybrid orbitals used in the bonding of atoms to to each other to form molecules? sp2 120 sp3 Hybrid Hybrid orbitals can accommodate the diverse shapes observed observed for molecules. (VSEPR) hybrid hybrid orbitals orbitals linear trigonal planar tetrahedral hybrid hybrid orbitals orbitals linear trigonal planar tetrahedral atomic atomic orbitals orbitals generally generally used for -bonds atomic atomic orbitals orbitals generally generally used for -bonds Why Why are hybrid orbitals used in the bonding of atoms to to each other to form molecules? Hybrid Hybrid orbitals can accommodate the diverse shapes observed observed for molecules. (VSEPR) Why Why are hybrid orbitals used in the bonding of atoms to to each other to form molecules? Hybrid Hybrid orbitals can accommodate the diverse shapes observed observed for molecules. (VSEPR) hybrid hybrid orbital orbital hybrid hybrid orbital orbital atomic atomic orbital orbital atomic atomic orbital orbital Hybrid orbitals can form stronger bonds. 3 9/8/2009 What orbitals are used to to form this -bond? A. Csp  Csp B. Csp  Csp2 C. Csp2 - Cp2 D. Csp2  Csp3 E. Csp3  Csp3 F. Cp - Cp What orbitals are used to to form this -bond? A. Csp3  Csp3 B. Csp  Csp2 C. Csp2 - Cp2 D. Csp2  Csp3 E. Csp3  Csp3 F. Cp - Cp HO O H H H H O HO -bond (Csp2-Csp2) H N O O O OH O N O O O O O O OH O O O O O O C C O O rapamycin 19 rapamycin 20 What orbitals are used to to form this -bond? A. Csp  Csp B. Csp  Csp2 C. Csp2 - Cp2 D. Csp2  Csp3 E. Csp3  Csp3 F. Cp - Cp What orbitals are used to to form this -bond? A. Csp  Csp B. Csp  Csp2 C. Csp2 - Cp2 D. Csp2  Csp3 E. Csp3  Csp3 F. Cp - Cp HO O HO -bond (Csp2-Csp2) H O O O OH O N O H H H O O O OH O N O O O O C C -bond (Cp-Cp) O O O O O O rapamycin 21 rapamycin 22 Planar Planar and nonplanar ethylene. Choose Choose the correct statement about nonplanar ethylene. planar H H C C H H H H nonplanar C C H H H H C C H H H C H C H H A. The p-orbitals of nonplanar ethylene form a bonding orbital. pof B. The p-orbitals of nonplanar ethylene form a non bonding orbital. pof non C. The p-orbitals of nonplanar ethylene form an anti bonding orbital. pof anti 4 9/8/2009 H H C C H H Estimate the rotational barrier of ethylene from the following bond dissociation data. C C CC H H C H 347 kJ/mole 607 kJ/mole 436 kJ/mole 413 kJ/mole A. 347 C. 260 H B. 607 D. 23 -bond broken bond -bond unchanged H D D H anti bonding molecular orbital H H C C H H H C H C H H H D C C H D C H C H H bonding molecular orbital non bonding molecular orbital C C Do Do sp hybridized orbitals still have p character? s + px sp sp Do Do sp hybridized orbitals still have p character? still character? sp3 p pp s + p C C C C + + 25% C C 27 75% 28 What What are the relative energies of s and p orbitals? orbitals? What What are the relative energies of s and p orbitals? orbitals? H s px py pz energy 29 C s px py pz energy s orbitals are more electronegative than p orbitals orbitals with more s character are more stable 30 5 9/8/2009 6 ...
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