09-08 - 9/8/2010 Why are hybrid rather than atomic orbitals...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 9/8/2010 Why are hybrid rather than atomic orbitals used in the bonding of atoms to each other to form molecules? O H C H Why are hybrid rather than atomic orbitals used in the bonding of atoms to each other to form molecules? O VSEPR hybrid orbitals linear atomic orbitals H C H Answer Answer this question using your Quiz/Workshop Quiz/Workshop form. Give two Give reasons. trigonal planar tetrahedral x y atomic 2s orbital 3 atomic 2p orbitals Z Why are hybrid rather than atomic orbitals used in the bonding of atoms to each other to form molecules? O Why are hybrid rather than atomic orbitals used in the bonding of atoms to each other to form molecules? O C VSEPR hybrid orbitals linear atomic orbitals two electron bond H C H H H hybrid orbitals trigonal planar H C tetrahedral linear trigonal planar tetrahedral All students whose class ID ends in All the number 3 should turn in their Quiz/Workshop form for credit! 1. Hybrid orbitals can accommodate the diverse shapes observed for molecules. (VSEPR) O H C H 1. Hybrid orbitals can accommodate the diverse shapes observed for molecules. (VSEPR) hybrid hybrid orbitals linear trigonal planar tetrahedral hybrid orbital atomic orbital two electron bond 1 9/8/2010 1. Hybrid orbitals can accommodate the diverse shapes observed for molecules. (VSEPR) 2. Because hybrid orbitals put a higher electron density between the atoms, they form stronger bonds. What orbitals are used to form this σ-bond? bond? A. Csp3 – Csp3 B. Csp – Csp2 C. Csp2 - Cp2 D. Csp2 – Csp3 E. Csp3 – Csp3 F. Cp - Cp HO O hybrid orbital σ-bond (Csp2-Csp2) H O O O OH O N O O O O C C atomic orbital two electron bond O rapamycin 8 What orbitals are used to form this π-bond? bond? A. Csp – Csp B. Csp – Csp2 C. Csp2 - Csp2 D. Csp2 – Csp3 E. Csp3 – Csp3 F. Cp - Cp Will the students with the following clicker serial numbers please see me after class. HO O σ-bond (Csp2-Csp2) H O O O OH O N O O O O C C π-bond (Cp-Cp) r2f686c, r2f6843, r2b6fc9 O rapamycin 9 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 What are the relative energies of s and p orbitals in atoms such as carbon? A. 347 347 B. 607 D. 23 π-bond broken H D σ-bond unchanged D H H D C. 260 C s px py pz energy s orbitals are more electronegative than p orbitals electrons in orbitals with more s character are more stable D 260 H D C C H D 607 C H C C C E 2 9/8/2010 Bond Energies C + H + heat (ΔH°) Bond Energies C + H C H + heat (ΔH°) What is the order of following reactions with respect to increasing heat released (∆H˚)? H H C H C + H H H C C H H Why would reaction ii be predicted to release the most heat? H H C H C + H H H C C H H i A. i < ii < iii increasing heat of reaction i sp2 sp B. i < iii < ii ii increasing heat of reaction H C C + H H C C H ii H C C + H H C C H C. ii < iii < i increasing heat of reaction H H C H C H + H H H H C C H H H H H C H C H + H H H H C C H H H iii H D. iii < i < ii increasing heat of reaction 13 iii H sp3 14 success! s p sp3 a lot of success but still under development. • molecular orbital theory • valence bond theory from the application of quantum mechanics to H· we can derive all of the atomic orbitals as well as their hybrids. resonance (Lewis) structures • molecular orbital theory • valence bond theory H1s H1s H· CH4 and larger molecules quantum mechanics 15 Orbital Energy H H 16 16 • valence bond theory resonance (Lewis) structures • molecular orbital theory For a C=C bond choose the π-antibonding molecular orbital from the following list. (A) (B) C C antibonding MO H H σ-antibonding molecular orbital σ-bonding molecular orbital C C H1s H1s Orbital Energy 435 kJ/mol (104 kcal/mol) (C) CC π-bonding molecular orbital bonding MO H H (D) 17 CC π-antibonding molecular orbital 18 Why is the bonding orbital more stable? 3 9/8/2010 • molecular orbital theory C C What role do antibonding orbitals play in your life? Photochemistry! • molecular orbital theory antibonding C C antibonding C C C2p C C C2p Csp2 Orbital Energy Csp2 420 kJ/mol (100 kcal/mol) Orbital Energy C C bonding C C bonding 20 What role do antibonding orbitals play in your life? • molecular orbital theory • molecular orbital theory C C antibonding C C antibonding color C C solar energy conversion C C C C bonding C C bonding vision vision What role do antibonding orbitals play in your life? • molecular orbital theory What role do antibonding orbitals play in your life? • molecular orbital theory C C antibonding C C antibonding C C C C C C bonding electric motor C C bonding solar energy conversion solar energy conversion 4 9/8/2010 What role do antibonding orbitals play in your life? • molecular orbital theory What role do antibonding orbitals play in your life? • molecular orbital theory C C antibonding C C antibonding C C C C electric generator C C bonding C C bonding displays light emitting diodes (LEDs) • valence bond theory resonance (Lewis) structures An alternative view of bonding • molecular orbital theory Draw the best Lewis (resonance) structure for formamide (CH3NO). O H C N H H C C antibonding start with correct structure formamide not H H C H N O C C C C bonding nitrosomethane 27 27 28 Draw the best Lewis (resonance) structure for formamide (CH3NO). O H C N H H 34567 B C NOF Si P S Cl Br I Choose the best Lewis (resonance) structure for formamide. O H C N H H 34567 B C NOF Si P S Cl Br I 1. add electrons 2. maximize bonding 3. add formal charges 1. add electrons 2. maximize bonding 3. add formal charges O O H C H formamide formamide O O A H C N H H BH C N H H C N H DH C N H H 29 30 5 9/8/2010 6 ...
View Full Document

Ask a homework question - tutors are online