Natural phenomena, explaining

However, if a hypothesis or set of hypotheses, based on an observation of a natural phenomenon, cannot be tested or experiments fail to show a direct conclusion, it is identified as a theory. A theory explains why something happens. For example, the atomic theory (see Lessons 9 and 10) of small electron particles orbiting around a dense nucleus containing protons and neutrons is based on indirect observations of the atom. This is only a possible explanation for the structure of an atom. A model is the description of the theory, such as the structure of an atom. 

A more natural phenomenon seems to be the oligo-oscillation, or the overshoot-undershoot phenomenon. These expressions denote the case when there is only a finite number of local extrema on the concentration versus time functions. Natural as it is, it has rarely been studied in a well-controlled experiment (see, however, Rabai et a/., 1979). It has also rarely been studied from the theoretical point of view. This situation can be explained by the fact that the qualitative theory of differential equations usually makes statements on long-range behaviour and much less on transient behaviour. The only exception seems to be that Pota (1981) has given a complete proof of the statement called Jost s theorem which says in a closed reversible compart-mental system of M components none of the concentrations can have more than M - 2 strict extrema. The methods used by Pota makes it possible to extend this result (see Problem 6 below). Another result of this type, relating nonlinear kinetic differential equations, can also be found among the Problems. 

MO bond order One-half the difference between the number of electrons in bonding and antibonding MOs. (340) model (also theory) A simplified conceptual picture based on experiment that explains how a natural phenomenon occurs. (9) molality (ro) A concentration term expressed as number of moles of solute dissolved in 1000 g (1 kg) of solvent. (404) molar beat capacity (C) The quantity of heat required to change the temperature of 1 mol of a substance by 1 K. (198) molar mass (il) The mass of 1 mol of entities (atoms, molecules, or formula units) of a substance, in units of g/mol. (73) molarity M) A concentration term expressed as the moles of solute dissolved in 1 L of solution. (99)... 

All this is a clear offense to ethics, that denies voluntary or involuntary manipulation of information, requires recognition of the professional competence, claims the assumption of responsibihties, avoids conflict of interest, places emphasis on self integrity, honesty and objectivity. Anyone substimting a scholar in explaining the science behind a natural phenomenon without having enough credit or giving advises about how to be prepared for a natural hazard without a consolidated experience commits an offence toward the principles of ethics. 

In most cases, the formation of complexes in molten salts leads to an increase in the molar volume relative to the additive volume. This phenomenon is usually explained by an increase in bond covalency. Nevertheless, the nature of the initial components should be taken into account when analyzing deviations in property values, as was shown by Markov, Prisyagny and Volkov [314]. In particular, this rule applies absolutely when the system consists of pure ionic components. The presence of initial components with a significant share of covalent bonds leads to an S-shaped isotherm [314]. 

The Group A emphases are those that inform the development of chemical literacy (DeBoer, 2000) and should be made available to all students (cf scientific literacy - (Roberts, 2007). These emphases all call for an imderstanding of a macro type of representation, so that learners appreciate what it is when they encounter a chemical phenomenon e.g. a solution, a colloid, a precipitate. This understanding would enable students to answer the question what is it and possibly what to do with it how to act when they encounter such a chemical phenomenon. These emphases also call for an understanding of the submicro type of representation, so that learners can qualitatively explain the nature of the macro phenomena that they encounter and hence be able to answer the question why is it as it is In order to explore these emphases, a chemistry curriculum would need to address a variety of contexts related to the three Group A emphases that have mearung in the everyday world. Pilot, Meijer and Bulte (2008) discuss three such contexts ceramic crockery, gluten-free bread and the bullet-proof vest. 

The phenomenon of attraction of masses is one of the most amazing features of nature, and it plays a fundamental role in the gravitational method. Everything that we are going to derive is based on the fact that each body attracts other. Clearly this indicates that a body generates a force, and this attraction is observed for extremely small particles, as well as very large ones, like planets. It is a universal phenomenon. At the same time, the Newtonian theory of attraction does not attempt to explain the mechanism of transmission of a force from one body to another. In the 17th century Newton discovered this phenomenon, and, moreover, he was able to describe the role of masses and distance between them that allows us to calculate the force of interaction of two particles. To formulate this law of attraction we suppose that particles occupy elementary volumes AF( ) and AF(p), and their position is characterized by points q and p, respectively, see Fig. 1.1a. It is important to emphasize that dimensions of these volumes are much smaller than the distance Lgp between points q and p. This is the most essential feature of elementary volumes or particles, and it explains why the points q and p can be chosen anywhere inside these bodies. Then, in accordance with Newton s law of attraction the particle around point q acts on the particle around point p with the force d ip) equal to... 

Having explained the origin of the adaptable (condition-dependent) character of molecular properhes, we now turn to illustrahons of this phenomenon. Indeed, stahng the variable nature of molecular properhes is not sufficient to appreciate its significance in drug design and SAR studies. 

It has been proven by experiment that there are donor acceptor atoms and molecules of absorbate and their classification as belonging to one or another type is controlled not only by their chemical nature but by the nature of adsorbent as well (see, for instance [18, 21, 203-205]). From the standpoint of the electron theory of chemisorption it became possible to explain the effect of electron adsorption [206] as well as phenomenon of luminescence of radical recombination during chemisorption [207]. The experimental proof was given to the capability of changing of one form of chemisorption into another during change in the value of the Fermi level in adsorbent [208]. 

When binding of a substrate molecule at an enzyme active site promotes substrate binding at other sites, this is called positive homotropic behavior (one of the allosteric interactions). When this co-operative phenomenon is caused by a compound other than the substrate, the behavior is designated as a positive heterotropic response. Equation (6) explains some of the profile of rate constant vs. detergent concentration. Thus, Piszkiewicz claims that micelle-catalyzed reactions can be conceived as models of allosteric enzymes. A major factor which causes the different kinetic behavior [i.e. (4) vs. (5)] will be the hydrophobic nature of substrate. If a substrate molecule does not perturb the micellar structure extensively, the classical formulation of (4) is derived. On the other hand, the allosteric kinetics of (5) will be found if a hydrophobic substrate molecule can induce micellization. 

Perhaps the most important toxicological role played by the GI tract is its influence over the absorption of chemicals that enter it. That absorption rates vary widely among chemicals has been explained in Chapter 2, but how the GI tract and its contents contribute to this phenomenon was not explained. Mechanisms of absorption are many and varied, and are influenced by the type and quantity of food present at the time of chemical ingestion, the pH (degree of acidity) of various portions of the GI tract, and even the nature and activity of the microorganisms that normally live in the intestines. In fact, metabolism of certain chemicals brought about by these microorganisms can play a crucial role, not only in their absorption, but also in the nature of the systemic toxicity they ultimately produce. 

---