Abstract: A molecular model has a center made up from two relatively pivotal parts which are angularly movable between predetermined angular positions. The parts are relatively unstable when not in such angular positions. Atomic valency bonds in the form of elongate flexible members extend from the pivotal parts and have at their free ends couplings which engage another like coupling of another flexible member or another center part. The couplings are identical and each comprises both a projection and a socket or in one embodiment a magnet presenting at an end surface, both a North and a South pole.

Abstract: A set of structural elements for making stereochemical models of molecules formed between polyvalent atoms. Each structural element has at least two connector arms representing the valences of an atom. An end portion of each arm is connected to an end portion of another connector arm, and the other end portion of each arm includes means for manually coupling and uncoupling the arm in an axial direction to the free end portion of another connector arm of the same element or to a connector arm of a further element. Said means for each arm is of the same configuration so that coupling can be effected without auxiliary means.