An application for visualizing the
aggregation of structureless atoms is presented. The application allows
us to demonstrate on a qualitative basis, as well as by quantitatively
monitoring the aggregate surface/volume ratio, that the enhanced
reactivity of nanoparticles can be connected with their large specific
surface. It is suggested that, along with the use of geometric analogies,
this bottom-up approach can be effective in discussing the enhanced
reactivity proprieties of nanoparticles. The application is based
on a two-dimensional realistic dynamic model where atoms move because
of their thermal and interaction potential energies, and the trajectories
are determined by solving numerically Newton’s laws according
to a Molecular Dynamics (MD) scheme. For this purpose, a web-based
MD engine was adapted as needed. It is suggested that, when possible,
using a realistic simulation rather than simple animations offers
several advantages in the visualization of processes of interest in
chemistry education. First, in a simulation the outcome of the process
under study is not set a priori but it is the result of the dynamic
evolution of the system; furthermore, specific parameters can be systematically
varied, and the effects of these changes can be investigated. The
application can be used at different levels of detail and in different
instruction levels. Qualitative visual observations of the growing
aggregates and of the progressive decrease of the reactive surface
are suitable at all levels of instruction. Systematic investigations
on the effect of changes of the atomic and aggregate sizes and temperature,
suitable for senior high school and college courses, are also reported.