How are molecular models different from other models?

Answer 1

Most models are always scaled-down versions of larger structures. They are structurally and aesthetically very similar to the objects that they represent, just smaller. Most commonly, they have been scaled down by factors of between 10 and 1000.

Molecular models are not like these models, though, and it is too easy to be fooled into thinking that they are, and the differences are greater than the similarities.

The first difference is that we are not scaling down, we are scaling up - and by huge factors: typically by the order of 10^10 (1 with ten zeros after it, ten trillion).

The direction and magnitude of the scaling, while curious, isn't a major difference - while relatively uncommon, there are models of microscopic objects such as spores or cells. The important distinction is that we're not creating enlarged replicas of the subject matter, because the atoms that we are modelling doesn't exist in a solid form as things do in the macroscopic world. We are attempting to produce physical models of concepts that are the result of mathematical descriptions (take a moment to get your head around that). Those mathematical models have assumptions & approximations imposed on them, such as larger atoms having hydrogen-like orbitals. We are creating physical models of a scientific model of a mathematical approximation. These aren’t models in the engineering sense; these are now illustrations of descriptions of reality. Seriously - what they represent doesn't exist in the way that they appear in molecular models.

Molecular models and crystal structure models cannot be replicas of the microscopic structures that they represent. Unlike engineering models, the qualitative difference between the quantum world and the macroscopic world is unbridgeable: we cannot create a scaled replica of that particular reality - and if we could, it wouldn't really help much anyway.

Molecular models show some of the following aspects of molecules or crystal structures:

• relative positions of atoms in the molecule or crystal
• the connections between atoms in the molecule or crystal
• the effective shape and volume of a molecule
• the coordination polyhedra around atoms
• the position of lattice planes in crystal structures.

There are no models that can show all of these, so you have to choose just a few of these at most to show in your molecular model.

Answer 2

Molecular models specifically represent the structure of molecules and how atoms are bonded together in a three-dimensional space. Other models may represent different aspects of a system, such as physical, mathematical, or conceptual relationships, without focusing on the structural arrangement of atoms in molecules. Molecular models are used in chemistry to visualize and understand molecular structures and interactions.