Molecular Model - Overview

Overview

Physical models of atomistic systems have played an important role in understanding chemistry and generating and testing hypotheses. Most commonly there is an explicit representation of atoms, though other approaches such as soap films and other continuous media have been useful. There are several motivations for creating physical models:

• as pedagogic tools for students or those unfamiliar with atomistic structures;
• as objects to generate or test theories (e.g., the structure of DNA);
• as analogue computers (e.g., for measuring distances and angles in flexible systems);
• as aesthetically pleasing objects on the boundary of art and science.

The construction of physical models is often a creative act, and many bespoke examples have been carefully created in the workshops of science departments. There is a very wide range of approaches to physical modelling, and this article lists only the most common or historically important. The main strategies are:

• bespoke construction of a single model;
• use of common materials (plasticine, matchsticks) or children's toys (Tinkertoy(TM), Meccano, Lego, etc.);
• re-use of generic components in kits (ca. 1930s to present).

Models encompass a wide range of degrees of precision and engineering: some models such as J.D. Bernal's water are conceptual, while the macromodels of Pauling and Crick and Watson were created with much greater precision.

Molecular models have inspired molecular graphics, initially in textbooks and research articles and more recently on computers. Molecular graphics has replaced some functions of physical molecular models, but physical kits continue to be very popular and are sold in large numbers. Their unique strengths include:

• cheapness and portability;
• immediate tactile and visual messages;
• easy interactivity for many processes (e.g., conformational analysis and pseudorotation).