Language for Chemical Reasoning

In Section III we will see how LCR (Language for Chemical Reasoning) meets these requirements. 

LCR (language for chemical reasoning see first chapter in this volume) to describe chemicals and their structure and atomic and molecular properties, as well as chemical reactions and their structure, directionality and contextual character. 

In NMR spectroscopy, however, the chemical shift measurement we make takes place in an environment of our making that is both entirely artificial and arbitrary (i.e., the magnet ). For this reason, it is essential to reference our measurements to a known standard so that we can all speak the same language, no matter what make or frequency of spectrometer we use. 

This term was introduced to the normal chemical language in the 20th century due to the efforts of Bodenstein. In Semenov s view, the understanding that, no matter how complicated is a reaction s process the law of the elementary act is sufficiently simple, is exclusively the credit "of Van t Hoff s genius prediction, though he himself did not understand it quite clearly [5, p. 6]. Though the epithet "genius with respect to Jacob Henri Van t Hoff is still valid, the situation, however, defies its complete reconstruction. On the one hand, it is likely that Van t Hoff renounced in principle the analysis of complex reactions that do not obey the laws of "normal conversions . Apparently, it is for this reason that in the "Etudes he did not examine etherification reactions practically [19]. Van t Hoff studied such simple reactions as the decomposition of dibromosuccinic acid and the reaction of... 

Chemistry is inside and around us all the processes that sustain life are based on chemical reactions, and most things we use in everyday life are natural (e.g., water, wheat, oil, wood) or artificial (plastics, glass, medicines, pesticides) molecules. For these reasons Chemistry is a central science. Its importance and extension can be better perceived by a comparison with language. Molecules, the words of matter, are the smallest entities that have distinct shapes, sizes and properties. Like words, molecules contain specific pieces of information that are revealed when they interact with one another. 

Just as Lavoisier stated 200 years ago, It is time to rid chemistry of obstacles of every kind... this reform must be brought about by perfecting the language, we postulate that a high-level (computer) language must be developed for meaningful advancement to occur in computer-aided chemical reasoning. 

In the language of chemical nomenclature, the simple names of atoms are the words. As words are assembled to form a sentence, so names of atoms are assembled to form names of chemical compounds. Syntax is the set of grammatical rules for building sentences out of words. In nomenclature, syntax includes the use of symbols, such as dots, commas and hyphens, the use of numbers for appropriate reasons in given places, and the order of citation of various words, syllables and symbols. 

IF there had been any English publication upon this curious and momentous subject, easy to be met with, that deserved regard, the public had not been troubled with this. The operations herein described are all within the compass of Nature they are laid down in plam language, and the reasoning upon them is suited to a common apprehension, where there is a chemical turn of mind. Anyone inclining to these studies, if poor, will do well to mind his proper business, without attempting the Philosophical Work, as the necessary apparatus must require more expense and time than he can spare but such as are of ability may well undertake it, both as a recreation and useful employment, in which an ingenious labourer may be retained as an assistant for the manual operations, at such a daily allowance as... 

The crystal chemical reason for polytypism is that adjacent layers (two-dimensionally-periodic units) can be linked to each other in many translationally nonequivalent ways. However, the nearest-neighbor relationships remain preserved. Translated into the language of symmetry, this means that the pairs of adjacent layers remain geometrically equivalent in all polytypes of the same family. 

Computers have been used for the storage and retrieval of scientific datasince the late 1960s. At first only punched cards and printers with the alphanumerical character set were available for a reasonable price. These facilities were insufficient for a good presentation of chemical structures. The Wiswesser line notation (WLN) was a workable substitute for structures, but it has never become a common language for the chemists. CROSSBOW and a few other programs became available but these batch-oriented programs are not user-friendly for bench chemists. They found them barriers instead of aids in communication. Therefore these systems were used mainly by intermediaries or information scientists. 

For technical reasons, MO theory is much easier to implement for numerical calculations on computers than VB theory is. The final test for any chemical theory is its fit with experimental data and the ease with which it can predict the structure, properties and reactions of molecules. A good compromise for numerical caicuiations is to use MO theory, which takes less computer time, and then to turn the result into the language of VB theory, which can be easier to visualize. This is known as a VB reading of MO theory. 

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