Tutorial 1
Tutorial 1Molecular Orbital Theory
1. Define molecular orbital theory.2. Define bonding and
antibonding molecular orbitals.3. Sketch the shapes of the
following molecular orbitals: 1s, 1s, 2p and 2p.4.Use the molecular
orbital theory to explain why Be2 does not exist.5.Draw the MO
diagram, write the electron configuration and calculate bond order
for these molecules. Also, decide whether the molecule is
diamagnetic or paramagnetic:a. N2b. F2c. Ne26.Explain the
significance of bond order.7.Can bond order be used to compare the
strengths of chemical bonds?8.Draw MO diagram and write electron
configurations for these species:d. F2, F2 -, F2+e. O2, O2 -, O22-,
O2+, O22+9.State the bond order for the species in Q5.10.Arrange
the following species in order of increasing stability: Li2, Li2+,
Li2-. Justify your choice with a molecular orbital energy level
diagram.
1. Sketch the constructive and destructive interactions of two
2p orbitals that produce:i) a sigma bonding and a sigma antibonding
molecular orbital.ii) a bonding and an antibonding pi molecular
orbital.
2. For a nitrogen gas (N2) molecule:i) State the HOMO and LUMO
of the N2.ii) Draw the orbital shape of the HOMO and LUMO of the
N2.iii) Would the N-N bond length be increased or decreased if an
electron is removed from N2 to form N2+? Explain your answer.
3. Molecular orbitals are formed when atomic orbital overlap.
Sketch the molecular orbitals formed when atomic orbitals below
interact.i) Two 2py orbitals destructively.ii) Two 2px orbitals
constructively.iii) One 2s orbital and one 2px orbitals.
4. Atomic orbitals can be linearly combined to produce bonding
and antibonding molecular orbitals. Draw the schematic diagram of
the formation of molecular orbital obtained when:i) An s and a px
atomic orbitals interact constructively,ii) Destructive interaction
of two py orbitals.iii) Two pz orbital overlap.
5. Use the Molecular Orbital Theory to explain the statements
below:i) The bond (dissociation) energy of H2 is higher than that
of H2+.ii) Removing an electron strengthen O2 but weakens N2. Draw
completely labeled molecular orbitial energy level diagrams to
substantiate your answer,iii) Draw the LUMO and HOMO of N2.
6. Consider the molecule O2 and the ion O22-.i) Construct and
label the MO energy level diagram for O2 and O22-. Include the
distribution of electrons,ii) State the magnetism of O2 and
O22-.iii) In which species is the O O bond stronger, O2 or O22-?
Explain your answer in terms of bond order. Is that bond longer or
shorter?iv) State the HOMO and LUMO for both O2 and O22-.v) Draw
the HOMO and LUMO diagrams.
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