Problems

Author: Hans Lohninger

Problem 1	Why does an electron shared by two nuclei have a lower potential energy than an electron on a single atom? Why does an electron shared by two nuclei have a lower kinetic energy than an electron on a single atom? How does this sharing result in a stable molecule? How can this affect be measured experimentally?
Problem 2	Explain why the bond in an H2 molecule is almost twice as strong as the bond in the H2+ ion. Explain why the H2 bond is less than twice as strong as the H2+ bond.
Problem 3	Be2 is not a stable molecule. What information can we determine from this observation about the energies of molecular orbitals?
Problem 4	Less energy is required to remove an electron from an F2 molecule than to remove an electron from an F atom. Therefore, the energy of that electron is higher in the molecule than in the atom. Explain why, nevertheless, F2 is a stable molecule, i.e., the energy of an F2 molecule is less than the energy of two F atoms.
Problem 5	Why do the orbitals of an atom "hybridize" when forming a bond?
Problem 6	Calculate the bond orders of the following molecules and predict which molecule in each pair has the stronger bond: C2 or C2+ B2 or B2+ F2 or F2+ O2 or O2+
Problem 7	Which of the following diatomic molecules are paramagnetic: CO, Cl2, NO, N2?
Problem 8	B2 is observed to be paramagnetic. Using this information, draw an appropriate molecular orbital energy level diagram for B2.