Chapter 9 Bonding and Molecular Structure Orbital Hybridization and Molecular Orbitals 1 Which of the following statements concerning molecular orbital MO bond theory is are CORRECT 1 MO theory can describe molecular bonding in excited states 2 MO theory accurately describes bonding in O2 and NO VB theory does not 3 MO theory predicts that electrons are localized between pairs of atoms 2 Which of the following statements concerning valence bond VB theory is are CORRECT 1 VB theory can describe molecular bonding in excited states 2 VB theory predicts that electrons are localized between pairs of atoms 3 VB theory correctly predicts the phase g or s of a molecule as a function of temperature 3 How many sigma bonds and pi bonds are in the following molecule a 1 only b 2 only c 3 only d 1 and 2 e 1 2 and 3 ANS D a 1 only b 2 only c 3 only d 1 and 2 e 1 2 and 3 ANS B a seven and three b seven and two c five and five d five and three e five and two ANS A a one s and three p b one s three p and one d c one s three p and two d two s six p and two d d two s six p and four d e ANS C 4 To form a molecule with an octahedral electron geometry what set of pure atomic orbitals must be mixed 1 5 What is the maximum number of hybridized orbitals formed by an oxygen atom 6 What is the hybridization of the central nitrogen atom in N2O 7 What is the hybridization of the sulfur atom in SCl2 8 What is the hybridization of the central sulfur atom in sulfur dioxide SO2 a 1 b 2 c 3 d 4 e 6 ANS D a sp b sp2 c sp3 d sp3d e sp3d2 ANS A a sp b sp2 c sp3 d sp3d e sp3d2 ANS C a sp b sp2 c sp3 d sp3d e sp3d2 ANS B a sp b sp2 c sp3 d sp3d e sp3d2 ANS E a Cl2CO b CO c CS2 d CH2Cl2 e HCN ANS D electrons a bent b linear 9 What is the hybridization of the central atom in a molecule with a square pyramid molecular geometry 10 For which of the following molecules does the carbon atom have sp3 hybridization 11 What is the molecular geometry around a central atom that is sp3 hybridized and has one lone pair of 2 12 What is the molecular geometry around a central atom that is sp3d2 hybridized and has two lone pairs trigonal planar trigonal pyramidal trigonal bipyramidal c d e ANS D tetrahedral trigonal bipyramidal of electrons a b c square planar d square pyramidal e see saw ANS C hybridization of carbon occurs in this reaction a sp to sp2 b sp2 to sp3 c sp3 to sp d sp2 to sp e sp3 to sp2 ANS D 13 Upon combustion ethene C2H4 is converted to carbon dioxide and water What change in the 14 Nitric acid HNO3 dissociates in water to form nitrate ions and hydronium ions What change in hybridization of the nitrogen atom occurs in this dissociation a sp2 to sp3 b sp2 to sp c sp3 to sp d sp to sp3 e no change ANS E Diagram 9 1 The molecular orbital diagram below may be used for the following problem s For oxygen and fluorine the 2p orbital should be lower in energy than the 2p However the diagram will still yield correct bond order and magnetic behavior for these molecules 2p 2p Energy 2p 1s 2s 2p 2s 1s 3 14 Refer to Diagram 9 1 According to molecular orbital theory which of the following species is the 15 Refer to Diagram 9 1 According to molecular orbital theory which of the following species is least most likely to exist i e which will have the greatest bond order 2 a H2 2 b F2 2 c N2 d Be2 2 e O2 ANS E 2 2 2 2 2 likely to exist i e has the lowest bond order a H2 b F2 c C2 d O2 e B2 ANS A 16 Refer to Diagram 9 1 According to molecular orbital theory which of the following species has the highest bond order a F2 2 b F2 2 c C2 d Li2 2 e B2 ANS C a 1 b 3 2 c 2 d 5 2 e 3 ANS C a 1 b 3 2 c 2 d 5 2 e 3 ANS D 2 2 2 2 2 a F2 b O2 c O2 d N2 e B2 17 Refer to Diagram 9 1 According to molecular orbital theory what is the bond order of oxygen N2 2 18 Refer to Diagram 9 1 According to molecular orbital theory what is the bond order of O2 19 Refer to Diagram 9 1 Use molecular orbital theory to predict which ion is paramagnetic 4 20 Refer to Diagram 9 1 What is the molecular orbital configuration of F2 ANS A core electrons 2s 2 2s 2 2p 4 2p 2 2p 2 a b core electrons 2s 2 2s 2 2p 2 2p 2 2p 2 core electrons 2s 2 2s 2 2p 4 2p 4 c d core electrons 2s 2 2s 2 2p 4 2p 2 2p 6 core electrons 2s 2 2s 2 2p 4 2p 2 2p 4 e ANS E core electrons 2s 2 2s 2 2p 4 2p 2 2p 2 core electrons 2s 2 2s 2 2p 2 2p 2 a b core electrons 2s 2 2s 2 2p 4 c d core electrons 2s 4 2s 4 e ANS B core electrons 2s 2 2s 2 2p 4 2p 2 2p 4 21 Refer to Diagram 9 1 What is the molecular orbital configuration of N2 2 5