Question

1) explain why there is no 2s-2p mixing in the MO enery-level diagram for F2, whereas 2s-2p mixing is evident in the MO energy-level diagram for Li2 ?

2) For the series of diatomics O2+, O2, O2- determine from an MO anery-level diagram how the bond lengths will vary and how many unpaird electron each should have?

3) The ionization enthalpies for H and F , draw an MO energy-level diagram for the HF molecule. How is the polarity of the molecule indicate in this diagram?

4) construct an MO enery-level diagram for NO, NO+, and NO-. determine the bonding order and the number of unpaired electrons in each.

5) Draw a qualitatively correct energy-level diagram for the CO2 molecule show that account correctly for the presence of double bond?

Answer 1

1) Energy gap 2s and 2p is more in F atom so there is no mixing 2s-2p in F2. But in Li atom there is less energy gap between 2s and 2p so there is a 2s-2p mixing.

2)

O2 has two unpaired electrons.

O2+ has one unpaired electron and O2 - also has one unpaired electron.

Bond length is inversely proportional to bond order.

O2- has shorter bond length and O2+ has longer bond length.

Order of bond lengths of species

O2+ < O2 <O2-