Module 9 1 Orbitals Theories 2 Valence Bond VB Theory a Orbital Overlap b Hybridization of Atomic Orbitals c Multiple Bonds 3 Molecular Orbital MO Theory ConcepTest Which is NOT a theory of molecular bonding A valence bond theory B molecular orbital theory C valence shell electron pair repulsion theory not really a theory D hybrid orbital theory not really a theory E all of these are theories about molecular bonding ConcepTest According to the valence bond theory which are TRUE I Likelihood of finding electrons between atoms increases true II molecules result from overlap between orbitals true III Four electrons occupy molecular orbitals two from each atom false A I only B II only C I and II D I and III E II and III F I II III Valence Bond Theory Orbital Overlap Bonds formed from overlap of atomic orbitals Orbital overlap increase probability of finding bonding electrons between atoms Two electrons opposite spin often one from each atom ConcepTest Which pair of atomic orbitals would you expect to ONLY form a sigma bond I s with s II s with p III p with p A I only B II only C I and II D I and III E II III F I II III Sigma bond overlap of orbitals end to end single bonds electron density greatest along axis of bond Pi bond side overlap 2nd or 3rd bond of a multiple bond C 2s22p2 2p 2s Hybrid orbitals explain observation of 4 CH equivalent bond in CH4 and account for number and symmetry mathematical or other manipulation of atomic orbitals add atomic orbitals Hybrid molecular orbitals name based what was used to make them 2 sp 3 sp2 4 sp3 5 sp3d 6 sp3d2 ConcepTest Which hybrid orbitals is not paired with the correct number of orbitals A sp3d2 6 B sp 1 C sp2 3 D sp3d 5 Don t confuse with electron configuration Hybridization of Atomic Orbitals Hybrid orbitals Sp orbitals two equivalent 180 apart p p AOs still left over Sp2 three equivalent 120 apart p AO left over Sp3 orbitals four equivalent 109 apart E sp3 4