The 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 53 plastic spheres 17-23mm in diameter, and 1 metal atoms-17mm in diameter. Bonds included are 30 medium connectors, 28 short connectors and 12 long flexible connectors.