History
In 1865, German chemist August Wilhelm von Hofmann was the first to make stick-and-ball molecular models. He used such models in lecture at the Royal Institution of Great Britain.
Specialist companies manufacture kits and models to order. One of the earlier companies was Woosters at Bottisham, Cambridgeshire, UK. Besides tetrahedral, trigonal and octahedral holes, there were all-purpose balls with 24 holes. These models allowed rotation about the single rod bonds, which could be both an advantage (showing molecular flexibility) and a disadvantage (models are floppy). The approximate scale was 5 cm per ångström (0.5 m/nm or 500,000,000:1), but was not consistent over all elements.
The Beevers Miniature Models company in Edinburgh (now operating as Miramodus) produced small models using PMMA balls and stainless steel rods. In these models, the use of individually drilled balls with precise bond angles and bond lengths enabled large crystal structures to be accurately created in a light and rigid form. Figure 3 shows a unit cell of ruby in this style.
Read more about this topic: Ball-and-stick Model
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