# Homework Problems Chapter 3

• • Kai Landskron
• Lehigh University
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## Homework Problems

### Section 1

Exercise 1

What will lead most likely to the smallest covalent interaction:

a) Overlap of a small and a large orbital.

b) Overlap of two small orbitals.

c) Overlap of two large orbitals.

a) Overlap of a small and a large orbital.

Exercise 2

a) orbital overlap in sigma-fashion

b) orbital overlap in pi-fashion

c) orbital overlap in delta fashion

a) orbital overlap in sigma-fashion

Exercise 3

Qualitatively construct the MO diagrams composed of

a) two 2s atom orbitals A and B of equal energy.

b) The orbital energy of atom A is significantly higher than that of B. Assuming both the bonding and the antibonding MO are filled with electrons: Where will bonding and antibonding electrons primarily be located. Explain briefly your decision. Exercise 4

Decide by “inspection” which of the following combinations of orbitals have the “right” symmetries to form molecular orbitals.

a) The 2px orbital of the first N atom and the 2py orbital of the second atom in the molecule N2. The z axis is defined as the bond axis in N2.

b) The 2px (of F) and the 1s orbital (of H) in the HF molecule. The z axis is defined as the bond axis.

c) The 2pz orbital of F and the 1s orbital in the HF molecule: The z axis is defined as the bond axis.

a) b) c) Exercise 5

The CH4 molecule belongs to the point group Td. You can find the character table of the point group in the internet.

a) Calculate the reducible representation for the ligand group orbitals (LGOs).

b) Calculate the irreducible representations of the ligand group orbitals (LGOs).

c) Draw a qualitative molecular orbital diagram for CH4. Exercise 6

Which are the symmetry types of the central atom orbitals in the PCl5 molecule?

1. Determine point group of PCl5. --> D3h.
2. Decide what are the valence orbitals of the central atom: 3s, 3p
3. Look up the character table of D3h, eg. in the internet. You will find their symmetries to be: A1' (3s), A2'' (3pz), E'(3px, 3py)

Exercise 7

For the hypothetical BrKr+ molecule: Toward which atom is the HOMO polarized? Explain briefly why.  Exercise 8

Reconstruct the MO diagram for water and NH3 (repeat what we did in class without looking at your notes (only use the respective character tables).

Water NH3 Dr. Kai Landskron (Lehigh University). If you like this textbook, please consider to make a donation to support the author's research at Lehigh University: Click Here to Donate.

This page titled Homework Problems Chapter 3 is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by Kai Landskron.