Organic chemistry Stick structure

Actual molecules do not in any way look like the ball-and-stick models. The sharing of electrons in the covalent bonds requires that the atoms of the molecule overlap as represented in Figure 1-5. However, the ball-and-stick models will suffice for our understanding of structural organic chemistry. 

The illustration program is a key component of the visual emphasis in Organic Chemistry. Besides traditional skeletal (line) structures and condensed formulas, there are numerous ball-and-stick molecular models and electrostatic potential maps to help students grasp the three-dimensional structure of molecules (including stereochemistry) and to better understand the distribution of electronic change. 

The picture of molecules being composed of structural units, functional groups , which behave similarly in different molecules forms the very basis of organic chemistry. The drawing of molecular structures where alphabetic letters represent atoms and lines represent bonds is used universally. Organic chemists often build ball and stick, or CPK space-filling, models of their molecules to examine their shapes Force, field methods are... 

Stereochemistry is that branch of chemistry concerned with the structures of compounds. The liberal use of simple stick models is highly recommended as a visual aid to the study of three-dimensional structures. Stereochemistry is sometimes considered to be solely a province of organic chemistry, but this is a gross misapprehension. Because of the unique extent to which carbon forms carbon-carbon chains, organic compounds have a large variety of shapes and structures. However, if attention is focused on an individual carbon atom, the four groups surrounding it are located at the comers of a tetrahedron. Furthermore, since carbon is a second-row element, only the s and p orbitals are available for bond formation. 

The term covalent was originally applied to the bonds in the ball and stick picture of structure used in organic chemistry. It is therefore interesting to note under what conditions the ball and stick picture can be derived from bond valence theory. The concept of a bond arose in the mid nineteenth century from the study of the chemistry of carbon compounds. The original model was simple it envisioned atoms as having a fixed number of hooks each of which could form a bond by linking to a similar hook on other atoms. This ball and stick picture, in which the balls represent the atoms and the sticks the bonds, can be derived from the bond valence theory if all the atoms have coordination numbers that are equal to their valence. Examples are silicon (V = N = 4), molybdenum (V = N = 6), and the two elements that form hydrocarbons carbon (V = N = 4) and hydrogen (V = N= 1). ... 

Stick RV (1997) The Synthesis of Novel Enzyme Inhibitors and Their Use in Defining the Active Sites of Glycan Hydrolases. 187 187-213 Stutz AE, see de Raadt A (1997) 187 157-186 Stumpe R, see Kim JI (1990) 157 129-180 Suami T (1990) Chemistry of Pseudo-sugars. 154 257-283 Suppan P (1992) The Marcus Inverted Region. 153 95-130 Suzuki N (1990) Radiometric Determination of Trace Elements. 157 35-56 Tabakovic I (1997) Anodic Synthesis of Heterocyclic Compounds. 185 87-140 Takahashi Y (1995) Identification of Structural Similarity of Organic Molecules. 174 105-134 Tasi G, Palinkd I (1995) Using Molecular Electrostatic Potentid Maps for Similarity Studies. 174 45-72... 

Another consequence of the fixed pores and the rigid structure (high DVB levels) is that macroporous resins have limited swelling. Thus a wide range of solvents commonly used in organic synthesis can be used in solid-phase macroporous resin assisted chemistry (even water), without modification of the reaction conditions as required for the use of gel-type resins. Moreover, the rigid structure makes these supports very resistant to mechanical agitation and easy to handle (macroporous resins do not stick like gel type resins). 

Chemistry is dehned as a study of the elements and their properties. Most of the time chemists are interested not so much in the elements themselves but rather in molecules, which are combinations of elements into discreet units. The organic chemist normally thinks of a molecule by reference to a rather simple model, usually of the ball-and-stick type. Such models are extremely useful for aiding in the visualization of three-dimensional interactions between molecules and between parts of molecules. But they are also a little bit misleading. A real molecule is not static, the way the usual mechanical model is. Rather, it is undergoing rapid motions, both internally and externally. Molecular structure can be defined at different levels, which are useful for different kinds of purposes. As we go past the ball-and-stick model, to the hard sphere model (space-filling model), and then to the soft sphere model (computational chemistry), we obtain an increasingly accurate description of the molecule and its properties. 

---