Over time, black and white drawings, first of stick figures, then of ball and stick models evolved into photographs of models and pictures showing orbital shapes. The advent of color illustrations about 10 years ago was a significant improvement, because the color could be keyed to different elements or to particular structural features of molecules. Textbook publishers offer sets of colored overhead transparencies so that lecturers have a source of images to project during lectures. Motion and Media But much of the content of chemistry is dynamic rather than static. Chemical objects are always in motion.
Electrons move around nuclei.
They absorb energy, jump to higher energy levels, and change the shapes of their orbitals. Molecules in a gas collide and bounce off one another like billiard balls. Chemical bonds are always vibrating and during reactions they break and new bonds form. Computer-based animated movies of these phenomena provide a new educational tool that can be used to directly and powerfully convey this dynamism to students. As recently as 1990, almost no production of animation or molecular visualization had occurred because the computers then available to chemistry instructors had inadequate power.