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Chapter 12

Study tips and resources for Chapter 12 – Physical Chemistry by Laidler, Meiser, Sanctuary

Bonding Part 4 – Molecular Orbital Theory

Difference between Valence Bond and Molecular Orbital for hydrogen

Screen grab of interactive multimedia animation showing difference between VB and MO for hydrogen (click to enlarge)

Now that we have discussed hybrid orbital theory and resonance theory, let’s finally turn our attention to molecular orbital (MO) theory.  The power of the MO theory is not in visualizing the molecule and its bonds, but in the ability to predict whether a molecule will exist and explain its characteristics.

For every combination of atomic orbitals, there are two possible molecular orbitals, bonding and anti-bonding.  The term anti-bonding merely means it is a higher energy possibility, not that it does not participate in bonding. Continue reading

Bonding Part 3 – Resonance Theory

Resonance theoryOnce again we explore the world of valence bond theory but this time only be concerned with molecules that have at least three adjacent p orbitals with electrons located in the pi bonds. What makes these molecules so unique is due to something called pi electron delocalization or resonance. While most valence bond theories require an exact location of electrons, resonance theory allows the pi electrons to exist in any adjacent p orbital. Continue reading

Bonding Part 2 – Hybrid Orbital Theory

How bonds are formed by overlapping of atomic orbitals

Click to enlarge

Valence bond theory (VB) and molecular orbital theory (MO) help explain why and how electrons are shared between atoms although their approaches are quite different.  Valence bond theory uses the individual atoms coming together with their atomic orbitals overlapping to pair electrons into covalent bonds.  Molecular orbital theory uses the idea of a positive nucleus surrounded by molecular orbitals.  Again, the two theories can be broken down into the “visual” and “predicting” realms.  I will explore each in different posts. Continue reading

A Look Into Bonding; Part 1 – Atoms


Screen grab of interactive VSEPR table (click to enlarge)

One of the most exciting parts of studying chemistry is the power to predict how atoms will combine into different molecules.  Of course, in order to do this, one must understand how the individual atoms behave alone and in close proximity to other atoms.  Chapter 12 of the physical chemistry textbook is devoted to chemical bonding and its two main theories:  valence bond theory (VB) and molecular orbital theory (MO). Continue reading

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Thermodynamics Module - Physical Chemistry
Thermodynamics module
Chapters 1 to 6 of Physical Chemistry - Laidler, Meiser, Sanctuary

Includes multimedia that opens on relevant pages and allows the student to visualize many of the concepts by varying parameters and plotting different graphs. Things students often have difficulty with, such as isothermal, isobaric, isochoric and adiabatic process, are clearly visualized.

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Physical Chemistry - Laidler, Meiser, Sanctuary
Physical Chemistry textbook
by Laidler, Meiser, Sanctuary

This popular Physical Chemistry text book is now available in electronic format. We have preserved much of the material of the former hard copy editions, making changes to improve understanding of the concepts in addition to including some of the recent discoveries in physical chemistry. Many chapters have new sections and the coverage of several chapters has been greatly expanded.

Get it from: Physical Chemistry - Laidler, Meiser, Sanctuary

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