Homework 05

1. (a) Sketch the occupied MOs of the valence shell for the N2 molecule. Label the orbitals as s or p orbitals, and specify which are bonding and which are antibonding.

(b) If one electron is removed from the highest occupied orbital of N2, will the equilibrium N-N distance become longer or shorter? Explain briefly.

2. (a) The ionization energy of molecular hydrogen (H2) is greater than that of atomic hydrogen (H), but that of molecular oxygen (O2) is lower than that of atomic oxygen (O). Explain. (Hint: Think about the stability of the molecular ion that forms in relation to bonding and antibonding electrons.)

(b) What prediction would you make for the relative ionization energies of atomic and molecular fluorine (F and F2)?

3. The MO of the ground state of a heteronuclear diatomic molecule AB is ymol = CAjA + CBjB .If a bonding electron spends 90% of its time in an orbital jA on atom A and 10% of its time in jB on atom B, what are the values of CA and CB? (Neglect the overlap of the two orbitals.)

4. According to recent spectroscopic results, nitramide

is a nonplanar molecule. It was previously thought to be planar.

(a) Predict the bond order of the N-N bond in the nonplanar structure.

(b) If the molecule really were planar after all, what would be the bond order of the N-N bond?

5. When one electron is added to an oxygen molecule, a superoxide ion (

) is formed. The addition of two electrons gives a peroxide ion (

). Removal of an electron from

leads to

(a) Construct the correlation diagram for

(b) Give the valence electron configuration for each of the following species:

(c) Give the bond order of each species.

(d) Predict which species are paramagnetic.

(e) Predict the order of increasing bond dissociation energy among the species.

6. Following the pattern of Figure 6.20 (see textbook), work out the correlation diagram for the BeN molecule, showing the relative energy levels of the atoms and the bonding and antibonding orbitals of the molecule. Indicate the occupation of the MOs with arrows. State the order of the bond and comment on the magnetic properties of BeN.


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