Carbon monoxide, CO, is iso-electronic to N2.
(a) Draw a Lewis structure for CO that satisfies the octet rule.
(b) Assume that the diagram in Figure 9.46 can be used to describe the MOs of CO. What is the predicted bond order for CO? Is this answer in accord with the Lewis structure you drew in part (a)?
(c) Experimentally, it is found that the highest-energy electrons in CO reside in σ-type MO. Is that observation consistent with Figure 9.46? If not, what modification needs to be made to the diagram? How does this modification relate to Figure 9.43?
(d) Would you expect the π2p MOs of CO to have equal atomic orbital contributions from the C and O atoms? If not, which atom would have the greater contribution?

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Small 2s-2p interaction Large 2s-2p interaction Ne2 π2p π2p σ2p σ2s σ2s ơ2s ơ2s Bond order Bond enthalpy (kJ/mol) Bond length (A) Magnetic behavior 290 1.59 Paramagnetic 620 1.31 Diamagnetic 941 1.10 Diamagnetic 495 1.21 Paramagnetic Diamagnetioc 155 1.43 N atomic orbitals NO molecular orbitals O atomic orbitals 2p 2p σ2p 2s 2s 2s σ2s O atom N atom NO molecule