The Structure of Matter

The notion that matter consists of discrete, indivisible particles (atoms) is quite ancient. The pre-Christian writers Lucretius and Democritus constructed elaborate speculative natural philosophies based on the supposition of the atomicity of matter. In the absence of experimental evidence to support them, these early atomic theories bore no fruit. 

Modern atomic theory is based on the quantitative observation of nature its first proposal by Dalton came after a period in which quantitative measurement had risen to importance in scientific investigation. In contrast to the ancient theories, modern atomic theory has been exceedingly fruitful. 

To put modern theory in some perspective, it is worthwhile to trace some of its development, at least in bare outline. We shall not attempt anything that could be dignified by the name of history, but only call attention to some major mileposts and courses of thought. 

The properties of matter are intimately tied to its structure, as we shall see in subsequent chapters, and the structure of matter is primarily determined by the sizes of the atoms and ions of its constituents and by the types of bonding between them. In this chapter, we will explore some of the myriads of ways nature has found to assemble materials, starting with simple one-component systems and then moving to compounds and finally to polymeric molecular structures. 

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David Turnbull, in his illuminating Commentary on the Emergence and Evolution of Materials Science (Turnbull 1983), defined materials science broadly as the characterisation, understanding, and control of the structure of matter at the ultramolecular level and the relating of this structure to properties (mechanical, magnetic, electrical, etc.). That is, it is Ultramolecular Science . In professional and educational practice, however, he says that materials science focuses on the more complex features of behaviour, and especially those aspects controlled by crystal... 

To learn chemistry, you must become familiar with the building blocks that chemists use to describe the structure of matter. These indude-... 

Regularities observed in the behavior of gases have contributed much to our understanding of the structure of matter. One of the most important regularities is Avogadro s Hypothesis Equal volumes of gases contain equal numbers of particles (at the same pressure and temperature). This relationship is valuable in the determination of molecular formulas—these formulas must be known before we can understand chemical bonding. 

These new facts about electrical phenomena can be incorporated into our particle model of the structure of matter if we again allow some... 

This success of the atomic theory is not surprising to a historian of science. The atomic theory was first deduced from the laws of chemical composition. In the first decade of the nineteenth century, an English scientist named John Dalton wondered why chemical compounds display such simple weight relations. He proposed that perhaps each element consists of discrete particles and perhaps each compound is composed of molecules that can be formed only by a unique combination of these particles. Suddenly many facts of chemistry became understandable in terms of this proposal. The continued success of the atomic theory in correlating a multitude of new observations accounts for its survival. Today, many other types of evidence can be cited to support the atomic postulate, but the laws of chemical composition still provide the cornerstone for our belief in this theory of the structure of matter. 

Such an approach is consistent with constructivism and follows the principle of induction by going from the macro to the submicro level. Note that the opposite approach, which starts from the structure of matter and follows a productive/receptive approach model, is quite common in chemistry education. 

Numerous studies have shown that students have great difficulties when trying to grasp concepts such as that of the molecule and the atom, i.e., when trying to move from the macro to the submicro level, and vice versa. Various researchers (e.g. Abraham, Williamson, Westbrook, 1994 Brook, Briggs, Driver, 1984, Haidar Abraham, 1991, Lee, Eichinger, Anderson, Berkheime, 1993, Novick Nuss-baum, 1981) have investigated students alternative conceptions. Herron (1978), Johnstone (1991) and Tsaparhs (1997) have stated the position that students have difficulties with concepts and topics relevant to the structure of matter. 

Keig, P. F., Rubba, P. A. (1993). Translations of the representations of the structure of matter and its relationship to reasoning, gender, spatial reasoning, and specific prior knowledge. Journal of Research in Science Teaching, 30(%), 883-903. 

Pfundt, H. (1982). Untersuchungen zu den Vorstellungen, die Schuler vom Aufbau der Stoffe en-twickeln [Investigations of the concepts students develop about the structure of matter]. Der Physikunterricht, 26, 51-65. 

State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Yangqiao Xi Road 155, PO Box 143 350002 Fuzhou, Fujian China... 

Much of the electromagnetic spectrum has been used to investigate the structure of matter in the laboratory but the atmospheric windows restrict astronomical observations from Earth. Irritating as this is for astronomers on the ground, the chemical structure of the atmosphere and the radiation that it traps is important to the origins of life on Earth. The light that does get through the atmosphere, however, when analysed with all of the tools of spectroscopy, tells the molecular story of chemistry in distant places around the Universe. 

University of Pennsylvania, Department of Physics and Laboratory for Research on the Structure of Matter, Philadelphia, PA 19104... 

Oscar Knefler Rice, Electronic Structure and Chemical Binding, with Special Reference to Inorganic Chemistry (New York McGraw-Hill, 1940) Francis Owen Rice and Edward Teller, The Structure of Matter (New York John Wiley, 1949). 

As science developed, our accumulation of knowledge about the structure of atoms and molecules was an achievement of early philosophers and scientists. These men and women did not use scientific procedures, but they did build the foundation of our current understanding of the structure of matter and how different species of matter interact. This history has led to our current understanding of the theoretical and practical nature of the chemical elements. 

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