This pack of green atoms are used to represent, typically, halogens atoms and is for extending your existing set or for replacing lost atoms. Each pack contains 10 balls with six holes arranged octahedrally. Each atom is 23 mm diameter.
Why would I need these? You could use them to represent octahedral chlorine in, say, a salt lattice.
The Molymod® system is the original, unique, dual-scale system of high quality low-cost molecular models. These enormously popular sets are ideal for students but are also used by scientists all over the world.