Integrated SequencePhysics Chemistry Organic Biology

Web Resources

  click if a link is broken

Special points of emphasis

Simple Harmonic Motion


The Chemical Bond

Intermolecular Forces

The Properties of Light

Molecular Spectroscopy

The mass-spring system is a useful model to help you gain insight into the vibrational behavior of chemical bonds and of vibrations along lines of intermolecular force. In other words, there is a fruitful interdisciplinary connection between the simple mechanics of harmonic motion and some important topics in chemistry.

Chemical behaior is rarely a pure reflection of the bare-bones model system from physics, but the basic physics is often an excellent starting point, so, although the relationship between force and separation is very different and, is, in fact, the chemical bond is a quantum-electrodynamic system, not encompassed by classical mechanics, let us consider a covalent bond an effective spring for a moment to help us understand certain aspects of its behavior.

Molecules vibrate and acquire vibrational energy. The relationships between electrostatic force, particle mass, and frequency (which produces a frequency of emitted radiation (infrared, microwave, etc.)) are similar to the relationships between spring constant, object mass, and frequency of spring oscillation. Larger masses and weaker forces give lower frequencies.

In organic chemistry, think about this the next time you look at the stretch vibrations in an IR spectrograph. Similarly to a weak spring connected to a large mass, thhrough their stretch vibrations, large atoms combined by weak bonds absorb lower energy (lower frequency) infrared photons than small atoms combined by strong, rigid bonds.

Although Hooke's Law most definitely does not describe the force vs. distance relationship of a covalent bond, it can be fruitful to think of covalent bonds as springs to relate bond strength and atom mass to stretch frequency.

The WikiPremed MCAT Course is a free comprehensive course in the undergraduate level general sciences. Undergraduate level physics, chemistry, organic chemistry and biology are presented by this course as a unified whole within a spiraling curriculum.

Please read our policies on privacy and shipping & returns.  Contact Us.
MCAT is a registered trademark of the Association of American Medical Colleges, which does not endorse the WikiPremed Course.

Creative Commons License
The work of WikiPremed is published under a Creative Commons Attribution Share Alike 3.0 License. There are elements of work here, such as a subset of the images in the archive from WikiPedia, that originated as GNU General Public License works, so take care to follow the unique stipulations of that license in printed reproductions. You can use the resources here for commercial or non-commercial purposes, but please give attribution and a link to the production credits and edit history of the resource. For the works here which began as my individual work, please attribute "John Wetzel, an author at".