Chapter 3 Quantum Mechanics

Question 1

1. Why are the energy levels of a hydrogenic atom (= one-electron atom) with atomic number Z different from that of a multi-electron atom with atomic number Z ?

Answer 1

Question 2

2. What is the ‘orbital approximation’ in the quantum theory of manyelectron atoms?

Answer 2

Question 3

3. Explain why the energy of a 2s orbital is lower than that of a 2p orbital in a many-electron atom? Why have both orbitals the same energy in a hydrogenic atom?

Answer 3

Question 4

4. Explain why the order of the energy levels in a shell of a many-electron atom is s < p < d < f.

Answer 4

Question 5

5. What are the values of the n, l and ml quantum numbers that describe the 4f orbitals?

Answer 5

Question 6

6. Consider the process of shielding in atoms, using Be as an example. What is being shielded? What is it shielded from? What is doing the shielding?

Answer 6

Question 7

7. What is the aufbau principle and the Madelung rule? Explain how these two are related.

Answer 7

Question 8

8. Demonstrate that the structure of the Left-Step Periodic Table reflects the filling of the atomic orbitals according to the Madelung Rule.

Answer 8

Question 9

9. Define the exchange energy, K. Calculate the exchange energies for the different d N configurations (N = 1–10)
10. Why is the ground state of an atom an electronic configuration with maximum spin multiplicity?

Answer 9

Question 10

11. Explain why the noble gases have higher ionization energies than those of the adjacent atoms.

Answer 10

Question 11

12. Although nickel, palladium and platinum have quite different ground state electronic conigurations, they all form square planar metal complexes. How can this be explained?

Answer 11