he molecular model set contains a number of different colored plastic spheres to represent various atoms. The atoms have holes at specific angles to accept plastic rods representing covalent and ionic bonds. The set allows you to build structural models of over 40 compounds. Set includes 84 plastic spheres 17-23mm in diameter, and 2 metal atoms-17mm in diameter. Bonds included are 60 medium connectors, 68 short connectors and 25 long flexible connectors.