5.1: Overview and Objectives

"Even the sense of taste and odor are based upon molecular configuration rather than upon ordinary chemical properties. A molecule that has the same shape as a camphor molecule will smell like camphor even though it may be quite unrelated to camphor chemically." (Linus Pauling)

Pauling was pointing out the relationship between a molecule's structure (the nature and arrangement of chemical bonds) and its function (how it interacts with other entities - in this case, the molecular receptors in our noses and mouths that are responsible for our sense of smell). This suggests that there are rules underlying chemical structure that control molecular function. There certainly are; and these rules come from quantum mechanics. In this chapter, we'll establish models for ionic, covalent, and metallic bonding. We'll look at covalent bonding in great detail, extending those quantum mechanical models to describe molecular shape and polarity. Lastly, we'll turn to one implication of polarity (structure) for how some molecules interact with water (function).

 

Chapter Objectives

• Identify bonding types in chemical compounds (ionic, covalent, or metallic). 

• Compare and contrast major theories of chemical bonding (Lewis, Valence-Shell-Electron-Pair Repulsion, Valence Bond Theory, Molecular Orbital Theory) 

• Draw Lewis structures, predict molecular geometry, and describe orbital hybridization according to accepted models of chemical bonding.

• Order covalent bonds by length, strength, energy, and polarity. 

• Predict whether a molecule/region of a molecule will be polar/nonpolar or hydrophobic/hydrophilic. 

• Predict the oxidation state, coordination number, spin state, magnetic properties, or color of a coordinate covalent complex.

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