Space filling molecular models: Starter set

cults3d

Space-filling molecular models offer an engaging visual representation of a molecule's actual volume, contrasting its connectivity. Computer graphics have largely replaced physical models for this purpose, but real-world models provide a tangible educational tool that can also delight cats and small children. This contribution introduces a starter set featuring tetrahedral carbon, oxygen, nitrogen, and two sizes of hydrogen atoms. "Why two sizes of hydrogen?" you might wonder. The explanation lies in the way hydrogen bonds with electronegative atoms like oxygen or nitrogen: it loses some electron density, causing its Van der Waals radius to decrease. "I thought covalent bonds involved equal sharing of electrons," you might say. Yes, but when atoms share electrons, they're more like kids playing a game – the stronger atom tends to dominate. These models adhere to the same scale as CPK models (1.25 centimeters per Angstrom) and are designed for educational purposes. The oxygen atom features a dihedral angle of 107 degrees, characteristic of alcohols. Inspired by Emmett's Parametric Snap Pins, the bonds require some force to insert but can be reused multiple times. To facilitate bond insertion, a tool is provided; however, using a dowel with an appropriate hole also works well. Be aware that the bonds may become less snug over time due to repeated use. The color of the atoms doesn't matter, and traditional colors have been used for this set.