The Structural Theory of Matter

In the mid-nineteenth century three individuals, working independently, laid the conceptual foundations for the structural theory of matter. August Kekuld, Archibald Scott Couper, and Alexander M. Butlerov each suggested that substances are defined by a specific arrangement of atoms. As an example, consider the structures of ammonium cyanate and urea from Wohler s experiment  

These compounds have the same molecular formula (CH4N2O), yet they differ from each other in the way the atoms are connected—that is, they differ in their constitution. As a result, they are called constitutional isomers. Constitutional isomers have different physical properties and different names. Consider the following two compounds  

These compounds have the same molecular formula (C2HgO) but different constitution, so they are constitutional isomers. The first compound is a colorless gas used as an aerosol spray propellant, while the second compound is a clear liquid, commonly referred to as alcohol, found in alcoholic beverages. 

Valencies of some common elements encountered in organic chemistry. 

Carbon generally Nitrogen generally Oxygen generally Hydrogen and halogens 

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Atomic stability and periodicity remain major issues in the structural theories of matter fortunately, they both have been largely solved by wave-particle (W/P) complementarily quantum behavior phenomenologically, such relationship can be expressed as WAVE PARTICLE = constant, while it may be quantized (by Planck s constant h) in the light of Heisenberg principle as (Putz, 2010, 2012)... 

By the 1920s, vitalism had been discarded. Chemists were aware of constitutional isomerism and had developed the structural theory of matter. The electron had been discovered and identified as the source of bonding, and Lewis structures were used to keep track of shared and unshared electrons. But the understanding of electrons was about to change dramatically. 

In his preface Gibbs describes the purpose of his treatise somewhat as follows The statistico-mechanical concepts and methods have so far been developed not as an independent system but only as an aid for the kinetic theory of matter. In this manner of developing the theory grave difficulties arose from the attempt to establish hypotheses about the structure of the gas models in such a way that they would account, if possible, for all experimental results. 

As to the content of Volume 20, the Editors would like to thank the authors for their contributions, which give an interesting picture of part of the current state of art of the quantum theory of matter from computational methods of optimizing the electronic energy and molecular conformations, over coupled-cluster expansion methods for the study of the open-shell correlation problem and the calculation of lifetimes of metastable states by means of the method of complex scaling, to a survey of the current state of surface structural chemistry. 

Progress in the physics of disordered media—that is, in the physics of media with a random distribution of microheterogeneity—is mainly made via the solution of problems involving the connection between the microscopic structure and the macroscopic behavior. This problem properly belongs to the realm of the kinetic theory of matter and is analogous to the problem of locking in the theory of fluids, hydrodynamic turbulence, the theory of phase transitions, and so on. 

One of the interesting things about thermodynamics is that although it deals with matter, it makes no assumptions about the microscopic nature of that matter. Thermodynamics deals with matter in a macroscopic sense it would be valid even if the atomic theory of matter were wrong. This is an important quality, because it means that reasoning based on thermodynamics is unlikely to require alteration as new facts about atomic structure and atomic interactions come to light. 

The particulate nature of matter is fundamental to almost every topic in chemistry. It involves the particle theory (often now called the kinetic molecular theory), which is the basis of explanations of atomic structure, bonding, molecules, much of solution chemistry and chemical reactions, equilibrium and chemical energetics. Because bonding (which involves atomic structure) and chemical reactions are covered in other chapters in this book, this chapter restricts itself to the particle theory of matter. Where useful, interesting aspects outside the particle theory are mentioned but the focus is fixed on the notion that all matter is composed of discrete, energetic particles that are separated by space. 

This represents only a fragment of the storylike structure of science (cf. p. 67), one of its most intriguing features. It makes science work otherwise, when considering the genetics of peas in biology, we would have to struggle with the quark theory of matter. 

THE ATOMIC THEORY OF MATTER THE DISCOVERY OF ATOMIC STRUCTURE (SECTIONS 2.1 AND 2.2) Atoms are the basic building blocks of matter. They are the smallest units of an element that can combine with other elements. Atoms are composed of even smaller particles, called subatomic particles. Some of these subatomic particles are charged and foUow the usual behavior of charged particles Particles with the same charge repel one another, whereas particles with unlike charges are attracted to one another. 

The Atomic Theory of Matter and the Discovery of Atomic Structure (Sections 2.1 and 2.2)... 

The important point that Lewis revealed is that though the acid-base properties of species are obviously modified by the presence or absence of a given solvent, their ultimate cause should reside in the molecular structure of the acid or base itself, and in light of the electronic theory of matter, not in a common constituent such as or OH, but in an analogous... 

Stlliman Lectures, 1903 Phil. Mag., 1904, vii, 237 1906, xi, 769 Electricity and Matter, 1904 The Corpuscular Theory of Matter, 1907 Rays of Positive Electricity, 1913, 2 ed. 1921 The Atomic Theory. The Romanes Lecture, Oxford, 1914 The Electron in Chemistry (Franklin Institute Lectures), 1923 see Hardin, Science, 1916, xliv, 655 (hist, of atomic structure). 

The atomic theory of matter infers that we can understand the world around us in terms of its smallest chemical components, atoms, whose structure of a massive, positively charged nucleus surrounded by lighter, fast moving electrons is widely taught. Several details of this model are important in building our knowledge of chemistry—... 

In the quantum theory of matter the study of the physical properties of any system, an atom, a molecule, or a solid, begins with the determination of the energy levels and the wave functions of the many electrons in the system. For this reason the theoretical and experimental investigations of the electronic structure of rare-earth metals have always occupied an important position in rare earth research. The pioneering calculations of the energy band structure of rare earth metals were motivated by the attempt to understand the complicated magnetic structures of these metals as revealed by neutron scattering. These... 

As noted in Chapter 1, all matter is composed of atoms. In this first part of Chapte 2, we explore the atomic theory of matter and the structure of atoms. We also examine the periodic table, which is an organizational chart designed to highlight similarities among the elements. 

The key here was the theory. The pioneers familiarity with both the kinematic and the dynamic theory of diffraction and with the real structure of real crystals (the subject-matter of Lai s review cited in Section 4.2.4) enabled them to work out, by degrees, how to get good contrast for dislocations of various kinds and, later, other defects such as stacking-faults. Several other physicists who have since become well known, such as A. Kelly and J. Menter, were also involved Hirsch goes to considerable pains in his 1986 paper to attribute credit to all those who played a major part. 

As we saw in Chapter 3, the founding text of modern materials science was Frederick Seitz s The Modern Theory of Solids (1940) an updated version of this, also very influential in its day, was Charles Wert and Robb Thomson s Physies of Solids (1964). Alan Cottrell s Theoretical Structural Metallurgy appeared in 1948 (see Chapter 5) although devoted to metals, this book was in many ways a true precursor of materials science texts. Richard Weiss brought out Solid State Physics for Metallurgists in 1963. Several books such as Properties of Matter (1970), by Mendoza and Flowers, were on the borders of physics and materials science. Another key precursor book, still cited today, was Darken and Gurry s book. Physical Chemistry of Metals (1953), followed by Swalin s Thermodynamics of Solids. 

What Are the Key Ideas Matter is composed of atoms. The structures of atoms can be understood in terms of the theory of matter known as quantum mechanics, in which the properties of particles and waves merge together. 

The modern theory of the electronic structure of the atom is based on experimental observations of the interaction of electricity with matter, studies of electron beams (cathode rays), studies of radioactivity, studies of the distribution of the energy emitted by hot solids, and studies of the wavelengths of light emitted by incandescent gases. A complete discussion of the experimental evidence for the modern theory of atomic structure is beyond the scope of this book. In this chapter only the results of the theoretical treatment will be described, These results will have to be memorized as rules of the game, but they will be used so extensively throughout the general chemistry course that the notation used will soon become familiar. 

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