BASIC CHEMICAL CONCEPTS

Homogeneous Catalysis Mechanisms and Industrial Applications, Second Edition. Sumit Bhaduri and Doble Mukesh. 

I n this chapter we discuss some of the basic chemical concepts that are of special relevance for homogeneous catalysis and metal complexes. Most homogeneous catalysts that we will discuss in this book are coordination or organometallic complexes of d elements. There are also a few complexes of f elements, i.e., lanthanides and actinides, that have shown promising catalytic activities, but their industrial use as homogeneous catalysts is insignificant. 

Broadly speaking, an organometallic complex belongs to a subset of coordination complexes and is supposed to have at least one metal-carbon bond. As a tribute to Alfred Werner for his pioneering work in the late nineteen and early twentieth century, coordination complexes are also known as Werner complexes. However, there are many coordination complexes that do not have any metal-carbon bond, but in terms of their properties and structures they resemble organometallic complexes. 

Two examples are shown by structures 2.1 and 2.2. Though there is no metal-carbon bond, the structure and properties of complex 2.2 are best understood by referring to that of 2.1, The latter is a classic organome-tallic complex called ferrocene. 

The catalytic behavior of a metal complex depends on many factors of which three are of major importance. These are the coordination geometry around the metal, the electronic and steric properties of the chemical moieties that are attached to the metal, and the number of electrons in the valence shell of the metal complex. Coordination numbers and coordination geometry simply mean the number of chemical moieties around the metal atom within bonding distances and their arrangements in three dimensions, respectively. 

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As noted, light-emitting diodes can be used to illustrate a variety of basic chemical concepts. Substitutional solid solutions like GaAsJPj (0 < x < 1) effectively extend the periodic table by providing a tunable band gap, which translates to tunability in the color of emitted light (4). 

We assume you re a high school or college student and have access to a secondary school-level (or higher) textbook in chemistry or some other basic primer, such as Chemistry For Dummies, 2nd Edition (written by John T. Moore, EdD, and published by Wiley). We present enough theory in this workbook for you to tackle the problems, but you ll benefit from a broader description of basic chemical concepts. That way, you ll more clearly understand how the various pieces of chemistry operate within a larger whole — you ll see the compound for the elements, so to speak. 

The hydrodesulfurization process can fall into either the destructive or nondestructive category. However for heavy feedstocks some hydrocracking is preferred, if not necessary, to remove the sulfur. Thus, hydrodesulfurization in this context falls into the hydrocracking or destructive hydrogenation category. The basic chemical concept of the process remains the same, that is, to convert the organic sulfur in the feedstock to hydrogen sulfide. 

In this chapter we will examine the basic chemical concepts of coprecipitation and solid solutions, and the partition coefficients of different elements and compounds in major sedimentary carbonate minerals will be presented. A brief summary of information on oxygen and carbon isotope fractionation in carbonate minerals will also be presented. A major portion of this chapter is devoted to... 

Transportation A student-driven, chemistry-based research project focused on campus transportation issues including estimations of carbon dioxide and smog-related pollutants resulting from campus activities. The project related directly to the course discussions of global warming, smog, local air quality, and air pollution regulations framed by basic chemical concepts such as chemical composition of the atmosphere, basic chemical reactions (e.g., combustion processes and photochemical reactions), stoichiometry of... 

In Chapters 2-8 we covered basic chemical concepts, which mostly fall under the headings structure1 (Chapters 2-4 and 7) and reactivity (Chapters 5, 6, and 8). These concepts are the bare bones supporting all of organic chemistry, and now wc shall start to put flesh on these bare bones. In Chapters 9-23 we will tell you about the most important classes of organic reaction in more detail. 

Here, we have had a glimpse of just one complex biological process. Yet we can begin to see how the understanding of biology rests on basic chemical concepts van der Waals forces and ion-dipole bonds polarity and solubility melting point and molecular shape configuration and conformation and, ultimately, the sequence of atoms in molecular chains. 

In this chapter, we have reviewed many of the basic chemical concepts and skills necessary for effective study of analytical chemistry. In the remaining chapters of this book, you will build on this firm foundation as you explore methods of chemical analysis. 

Lavoisier s vision of the mathematization of chemistry placed him in the Newtonian tradition of ethers and imponderable subtle fluids. In shifting the focus of the Chemical Revolution away from the originality of Lavoisier s experiments on combustion and towards the power, fruitfulness and intellectual context of his basic chemical concepts and categories, postpositivist scholars undermined the positivist-Whig notion of Lavoisier s crucial year and any clear sense of its cruciality . ... 

Through these simulations, students appreciate the energetic and kinetic aspects of chemical reactions and why the composition of the atmosphere is critical to the outcome. For example, the class simulates the effect on the yield of amino acids if the atmospheric composition was CO2 instead of CH4 or the nitrogen source was N2 instead of NH3. The simulations also allow students to investigate the consequences if the pre-biotic atmosphere contained free 02. Through these simulations, basic chemical concepts are discussed including thermodynamics, thermochemistry and bond enthalpies, kinetics, and catalysis. 

The basic chemical concept of the hydrodesulphurization (HDS), hydrodenitrogenation (HDN) and hydrodemetallation (HDM) processes is to remove selectively the heteroatoms and metallic species from the organic moiety. 

In addition we will consider the possibility to obtain reliable theoretical information on the preferred attach sites for proton and metal cations and on the potential energy surfaces (PES) that cannot be determined experimentally even with the most modern and sophisticated mass-spectrometric instruments [22,23j. Furthermore, we will propose the way to rationalize some of chemical properties by using the concepts of hardness, softness and other reactivity indices (Fukui functions) for which an exact definition exists only in the framework of DFT 1111. These last fascinating tools can contribute to increase funhemiore the DFT use going in the "core" of molecules to predict and explain basic chemical concepts. 

This is a reminder of (or introduction to) basic chemistry. If you have recently done and understood school or college chemistry, you can probably skip the whole of the next two chapters, which are here to make sure that everyone is happy with atoms, molecules, valency and other basic chemical concepts that we are going to need to use and take for granted as we move on through the biochemistry. 

Nentwig, P., Demuth, R., Parchmatm, I., Grasel, C., Ralle, B. (2007). Chemie im Krurtext Situating learning in relevant contexts while systematically developing basic chemical concepts. Journal of Chemical Education, S4(9), 1439-1444. 

Mandado M, Gonzalez Moa MJ, Mosquera RA (2008) Aromaticity exploring basic chemical concepts with the quanmm theory of atoms in molecules. Nova Science Pubhshers, Inc., New York... 

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