Analogies and Metaphors

The actual form of a molecule having resonance structures is like a central party in politics, a moderate denomination in religion, the liquid state of matter, or mixing red and blue liquids.
1. The extremes define and "bracket" an intermediate concept, theory, or idea. Frequently, something is described by saying what it is not like. For example, "Dan, I'm glad I'm not that narrow-minded." The terms liberal Republican, conservative Democrat, and orthodox Jew, for example, are used to convey deviation from, or strict adherence to, an idea or concept. The British Social Democratic Party was founded to offer a centrist alternative to more extreme positions of the ruling Conservatives on the right and the Labour Party on the left.

   Likewise, the liquid state lies between the solid state and the gaseous state in the sense that it is less dense than the solid state and more dense than the gaseous state. Solids and gases are extremes. Solids are usually very ordered in the arrangement of their atoms and molecules, whereas gases show no ordered arrangement of their atoms and molecules. Liquids have a "short-range order", but no "long-range order." So the liquid state has been defined by what it is not like.

2. Orthodox (or fundamental) religion, and right and left wing extremism in politics are common terms. Orthodoxy and fundamentalism imply strict adherence to an idea or a concept. A specific chemical "resonance structure" is "orthodox"-it is exactly that structure and nothing else! A different resonance structure of the same molecule is that extreme as written and nothing else. However, the concept to be conveyed by the idea of resonance is that the actual molecule for which resonance is possible is none and yet all of the extreme or orthodox forms. It is and intermediate among resonance forms that we are able to define and draw.

3. When blue and red colors are mixed (dye solutions, for example) the resulting color is neither blue nor red, but something intermediate. In other words, a "resonance hybrid" of the two individual colors. This might be illustrated as follows:
   Blue + Red -> Purple

4. The picture of "extreme religions" or political parties as developed in the context of the chemical concept of resonance furnishes a good lead into a discussion of resonance. Remember, the "resonance" concept implies the existence of many facets, faces, and forms, but the real picture is none of those extremes entirely!

   
   

The covalent bond illustrated by the two friends sharing an ice cream cone is like a single covalent bond, sometimes called a sigma (s) bond. If, while sharing the cone, they also share the burden of carrying a canoe overhead, this would be like a double covalent bond, sometimes called a pi (π) bond.

Bonding is a term commonly used in contexts other than in chemistry. Discuss the following statements as common examples of the use of the term bonding.
1. "I'm really bonded to the Rocky Mountains because I was born in Colorado Springs."

2. "I'm really bonded to the Texas Hill country because my grandmother's house was only fifty miles from Austin."

3. The accused house burglar had to post a $5000 bond to appear in court.

4. "My uncle gave me a $50 U.S. Savings Bond when I was ten years old."

   
   

Teflon-coated stirring bar magnets on an overhead projector can be used to illustrate an analogy between magnet behavior and polar molecule behavior. If the stirrers are spaced away from each other with a random orientation, then when a magnet passes near them on the overhead light stage, the magnetic stirrers will torque to align themselves parallel to the magnet's magnetic field. Polar covalent molecules behave similarly in an electric field.

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