Chemical cohesion

The question of molecular structure and shape is considered in the next chapter. It will be shown that the familiar molecular structure is a function of chemical history and the thermodynamic environment. It is emphasized, in particular, that experimental determination of molecular structure is strictly confined to the solid crystalline state. 

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There are several reasons for this unsatisfactory state of affairs. Most important is perhars the different conceptual demands on theories of chemistry and physics respectively. In this instance there has been no effort to re-interpret mathematical quantum theory to satisfy the needs of chemistry. The physical, or Copenhagen, interpretation, which is essentially an ensemble theory, is simply not able to handle the individual elementary units needed to formulate a successful theory of chemical cohesion and interaction. Computational dexterity without some mechanistic basis does not constitute a theory. Equally unfortunate has been the dogmatic insistence of theoretical chemists to drag their outdated phenomenological notions into the formulation of a hybrid theory, neither classical nor quantum even to the point of discarding... 

Constitutional formulae were designed "on paper", primarily to be "in harmony" with known chemical properties and without pretension to "represent the symmetrical or spatial arrangement of the atom in a compound" [22], Not only was this stipulation gradually relaxed to represent three-dimensional structures, but the connecting lines were also soon after assumed to represent definite electronic links between atoms. This assumption opened the door for the introduction of semi-empirical quantum-mechanical characterization of chemical bonds. It is important to realize that chemical bonds have never been observed in any experiment and that they only exist as conjectures to interpret primitive molecular graphs. Their value as heuristic aids in the study of chemical change and composition is beyond dispute, but as a basis for the theoretical understanding of chemical cohesion they are of little value. 

The quantum content of current theories of chemical cohesion is, in reality, close to nil. The conceptual model of covalent bonding still amounts to one or more pairs of electrons, situated between two atomic nuclei, with paired spins, and confined to the region in which hybrid orbitals of the two atoms overlap. The bond strength depends on the degree of overlap. This model is simply a paraphrase of the 19th century concept of atomic valencies, with the incorporation of the electron-pair conjectures of Lewis and Langmuir. Hybrid orbitals came to be introduced to substitute for spatially oriented elliptic orbits, but in fact, these one-electron orbits are spin-free. The orbitals are next interpreted as if they were atomic wave functions with non-radial nodes at the nuclear position. Both assumptions are misleading. 

Although the physics model may give a reasonable qualitative account of chemical concepts, such as chemical cohesion, it fails at the quantitative level, because essential factors are ignored. The most important factor is the environment. The free atom of physics represents a universe, completely empty, except for a solitary atom. Such an atom can never explain chemical effects, which occur because of the interaction of an atom with its environment. When the total environment is taken into account one deals with the familiar classical macro world. Between the two extremes is chemistry and it is important to know whether to describe chemical entities, like molecules, in classical or non-classical terms. 

All terms in equation (6.2) are therefore accounted for. It remains to show that the essential concepts of force constant and bond parameter free of strain also have well-defined meaning in the theory of chemical cohesion. 

Chemistry remains a mystery without understanding three basic attributes of matter cohesion, structure and affinity, each of them shaped by an extremum principle. The principle of minimum energy regulates chemical cohesion, which results from the interaction between atoms, also known as chemical bonding. Minimization of angular momentum dictates the three-dimensional arrangement of atoms in chemical substances, which defines their... 

Matter in general is made possible by the inseparable bond between attraction and repulsion. Because the proportion of these forces may vary, the possibility of an infinite variety of chemical substances is given. Hence, the first causes are not mechanical (as in atomist theories), but physico-dynamic.69 The interaction between the omnipresent ether and the two originary forces creates the specific differences between types of matter. Each chemical substance is characterized by a quantity of ether and three forces [universal attractive force, proper repulsive force, and proper attractive force (chemical cohesion)]. Hence, the ether is the ultimate origin of the variety of substances (together with the two moving forces). 

On 29 June 2006, the European Commission through its Directorate D Water, Chemicals Cohesion, D1, submitted to the Secretariat of the Stockholm Convention a letter requesting consideration of three candidate POPs for inclusion to the Stockholm Convention. These three chemicals submitted to the second meeting of the POPRC were the following ... 

There are two basic ways of joining the hard and soft components of a composite, chemical and mechanical [14], A purely mechanical joint is obtained by overmolding apertures or undercuts in the hard component. The use of internal or external adhesion promoters permits the production of composites with liquid-tight frictional joints [15], A bond formed by chemical cohesion has a number of advantages over a mechanical joint formed by interlocking [16] ... 

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