Balls and sticks model

All pictorial representations of molecules are simplified versions of our current model of real molecules, which are quantum mechanical, probabilistic collections of atoms as both particles and waves. These are difficult to illustrate. Therefore we use different types of simplified representations, including space-filling models ball-and-stick models, where atoms are spheres and bonds are sticks and models that illustrate surface properties. The most detailed representation is the ball-and-stick model. However, a model of a protein structure where all atoms are displayed is confusing because of the sheer amount of information present (Figure 2.9a). 

It should be remembered once more that the use of molecular models ("ball-and-stick". as well as Dreiding or similar) is always essential for fully understanding the conformational and configurational changes involved in multistep syntheses of complex organic compounds... 

A structural model is a three-dimensional representation of the structure of a compound. There are two kinds of structural models ball-and-stick models and space-filling models. Figure 13.6 shows ball-and-stick models for the five isomers of C6Hi4. Notice that they show how the carbon and hydrogen atoms are bonded within the structures. 

Ball-and-stick models. Ball-and-stick models are not as realistic as space-filling models, because the atoms are depicted as spheres of radii smaller than their van der Waals radii. However, the bonding arrangement is easier to see because the bonds are explicitly represented as sticks. In an illustration, the taper of a stick, representing parallax, tells which of a pair of bonded atoms is closer to the reader. A ball-and-stick model reveals a complex structure more clearly than a space-filling model does. 

Molecular models (ball and stick models, space-filling models) which reproduce typical bond lengths and bond angels and hence stereochemical and congestional effects. However, certain aspects are not covered by the model they are, for instance, not soluble in cyclohexane in the same way as the original. 

Space-filling model Ball-and-stick model... 

BaU-and-stick model Ball-and-stick model viewed from the side viewed from above... 

Note that the four hydrogen atoms are distributed to the corners of an imaginary tetrahedron in three-dimensional space around the carbon of 4d, which is buried in the center of the tetrahedron. In addition, a three-dimensional molecular model of methane is shown where cylinders represent the bonds and spheres represent the atoms (4e), which is the so-called ball-and-stick model. The bonds represented by wedges and dashed lines in the two-dimensional model are marked in 4e. A so-called space-filling model, 4f, is also shown to illustrate the relative size of the atoms. Both types of molecular models (ball and stick or space filling) will be used for other molecules in various places in the book. 

Fig. 5.12 Models (ball-and-stick, l -hand side, CPK p-lactam ring confers rigidity on the molecule with the space-filhng, right-hand side) shovring some possible linked peptide at C-2 (shown here attached to a sin-...

Stichverletzung (Nadel etc.) stick-and-ball model/ ball-and-stick model Stab-Kugel-Modell, Kugel-Stab-Modell stickiness/tack Klebrigkeit... 

Material models such as coloured plastic molecular scale models (ball-and-stick models, space-filling models),... 

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