Molecular models are important learning tools even now with computer versions available. Physical models help understand naming functional groups, see the importance of atom geometry, molecular symmetry, bond rotation & more. Teaching chemistry in an auditorium? Then you need extra large molecular models.
Organic Chemistry: Naming Functional Groups
The diversity of organic compounds is directly related to functional groups and their roles in both reactivity and geometry. A good example of this is the different groups with oxygen: alcohols, aldehydes, carboxylic acids, esters, ethers, ketones, and phenols. Many of these differences are quite subtle and can be a challenge to discern in models without explicit atom centres. In large lectures halls, this omission is even more apparent.
Extra Large Models for Molecular Symmetry
Point groups and molecular symmetry are topics generally covered in advanced-level inorganic chemistry. However, the ease of rotation of these large models is useful not only for molecular symmetry but also for organic chemistry in general.
For point group use, both the planes and centers of symmetry can be distinguished. For organic chemistry, rotating sections of models can demonstrate differences in reaction energies, steric hindrances, and potential sites for chemical attack when discussing reaction mechanisms.
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Extra Large Molecular Models for Chirality
Chirality or handedness is a key concept in organic chemistry and is especially important for understanding chemical activity in biomolecules such as amino acids. The image below shows a simple chiral pair in the lecture Hall-sized Unit models with its Orbit equivalent for size comparison.
The larger Unit models stand roughly 200mm (8″) tall while the smaller Orbit style equivalents are only about 75mm (3″) tall. Note that both have distinct atom centers, unlike wireframe models.
Extra Large VSEPR Models
VSEPR (valence shell electron pair repulsion) theory predicts the shape molecules take on account of the effect of unpaired electrons. For example, methane has a tetrahedral shape based on a central carbon and 4 hydrogens. Water consists of oxygen, 2 hydrogens, and 2 pairs of unbonded electrons. Its shape very nearly approximates that of methane.
Compare the size between the lecture hall linear model shown in the image below & a similar model built with our Orbit style basic VSEPR theory model set. The lecture hall sized model is 300mm (12″) vs 50mm (2″).
Lecture Hall sized VSEPR Theory molecular models. The linear model in front is about 300mm (12 inches) from end to end. Not shown are optional electron pair paddles.
Crystal Lattices & Unit Cells
Unit models are so named because they were designed for building “unit cells” of crystal lattice structures. Unit cells are the minimum building blocks of larger crystal structures. These include many familiar materials such as diamond, sodium chloride (table salt), ice, and many thousands more. The Unit model system is particularly useful for showing the 7 basic crystal systems.
Aside from being the largest commercially available molecular models, they are the only ones capable of 12 coordinate geometry. In other words, they can connect to 12 other atoms as shown in the model of Titanium Gold (Ti3O) depicted below.
Unit style atoms and bonds are economical large-format molecular structure models that can depict higher-order coordination, especially important for metals.
The Takeaway
First-year at university can be stressful especially when the course material is unfamiliar. Organic chemistry can be particularly hard on the biology students competing for pre-med positions. Wireframe molecular models, best reserved for 3rd & 4th-year chemistry majors, only add to this stress. These extra-large models can make the learning experience more productive and meaningful.
