Abstract: A three-dimensional molecular model comprises plastic modules, each representing on atom connected to one another. Modules intended to represent atoms of cyclic compounds are polyhedrons set in the model so that adjacent polyhedrons touch faces and have a common apex. The sum total of the angles formed by the adjacent faces of polyhedrons of the modules is more than 360.degree..

Abstract: A three-dimensional model of molecular structure comprises plastic modules and their connecting elements which are made as cylindrical rods whose entire surface, as well as the mating surface of sockets of the modules, is provided with easily curved projections alternating with depressions of the same shape. To assemble or disassemble said three-dimensional model use is made of a device, whose jaws each have a wider portion to hold the module and are bent, and the inner surface of the jaws being provided with wedge-like projections to facilitate disassembly of the modules.

Abstract: The three-dimensional model of a molecular structure comprises plastic modules (1) interconnected by connecting members (2). Each module (1) has an element (6) of an X-ray contrast material at its center, and an insert (7), also of an X-ray contrast material, extends axially of each connecting member (2).