Concept explainers
The energy-level diagram in Figure 9.36 shows that the sideways overlap of a pair of p
orbitals produces two molecular orbitals, one bonding and one antbonding. In ethylene there is a
pair of electrons in the bonding n orbital between the two carbons. Absorption of a photon of the
appropriate wavelength can result in promotion Of one Of the bonding electrons from the r2p to the
Ir. molecular orbital.
a. Assuming this electronic transition corresponds to the HOMO-LUMO transition, what is the
HOMO in ethylene?
b Assuming this electronic transition corresponds to the HOMO-LUMO transition, what is the
LUMO in ethylene?
c. Is the bond in ethylene stronger or weaker in the excited State than the ground state?
d. Is the C-C bond in ethylene easier to twist in the ground state or in the excited state?
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Laboratory Experiments for Chemistry: The Central Science (14th Edition)
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- a Nitrogen trifluoride, NF3, is a relatively unreactive, colorless gas. How would you describe the bonding in the NF3 molecule in terms of valence bond theory? Use hybrid orbitals. b Silicon tetrafluoride, SiF4, is a colorless gas formed when hydrofluoric acid attacks silica (SiO2) or glass. Describe the bonding in the SiF4 molecule, using valence bond theory.arrow_forwardA useful solvent that will dissolve salts as well as organic compounds is the compound acetonitrile, H3CCN. It is present in paint strippers. (a) Write the Lewis structure for acetonitrile, and indicate the direction of the dipole moment in the molecule. (b) Identify the hybrid orbitals used by the carbon atoms in the molecule to form bonds. (c) Describe the atomic orbitals that form the n bonds in the molecule. Note that it is not necessary to hybridize the nitrogen atom.arrow_forwardTrue or false: Boron contains 2s22p1 valence electrons, so only one p orbital is needed to form molecular orbitals.arrow_forward
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- a. One of the two known binary compounds of xenon and oxygen is XeO3. A Lewis structure is shown here, which may or may not be complete. How many lone pairs should be present on the central Xe atom? b. What is the electron pair geometry around the Xe? c. What is the molecular geometry of XeO3? d. What hybrid orbitals does the Xe atom use?arrow_forwardDraw the molecular orbital diagram (MOD) for the following molecules. Use their potential energy to obtain the energy of different orbitals. When drawing the MODs, clearly indicate whether the MO’s are sigma /pi, bonding, antibonding or non-bonding orbitals. a. O2 and calculate bond order b. N2 and calculate bond order c. CO and calculate bond order d. NO and calculate bond orderarrow_forwardConsider a NF molecule a. Draw orbitals of each atorn and find possible interactions among them. b. Draw atomic orbitals. using the potential energy information c. Draw molecular orbitals from the atomic orbitals of N and F. d. What is the band order of this molecule? e. Specify the types of molecular orbitals, or (NF,NF? Which of the three has the longest bond length -NF, NF, and NF ? Explain your answer.arrow_forward
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