Bulk matter

Why Do We Need to Know This Material In the first three chapters, we investigated the nature of atoms, molecules, and ions. Bulk matter is composed of immense numbers of these particles and its properties emerge from the behavior of the constituent particles. Gases are the simplest state of matter, and so the connections between the properties of individual molecules and those of bulk matter are relatively easy to identify. In later chapters, these concepts will be used to study thermodynamics, equilibrium, and the rates of chemical reactions. 

Molecules am act one another. Fiuni that simple fact spring fundamentally important consequences. Rivers, lakes, and oceans exist because water molecules attract one another and form a liquid. Without that liquid, there would be no life. Without forces between molecules, our flesh would drip off our bones and the oceans would be gas. Less dramatically, the forces between molecules govern the physical properties of bulk matter and help to account for the differences in the substances around us. They explain why carbon dioxide is a gas that we exhale, why wood is a solid that we can stand on, and why ice floats on water. At very close range, molecules also repel one another. When pressed together, molecules resist further compression. 

The expressions in Eq. 1 and Eq. 6 are two different definitions of entropy. The first was established by considerations of the behavior of bulk matter and the second by statistical analysis of molecular behavior. To verify that the two definitions are essentially the same we need to show that the entropy changes predicted by Eq. 6 are the same as those deduced from Eq. 1. To do so, we will show that the Boltzmann formula predicts the correct form of the volume dependence of the entropy of an ideal gas (Eq. 3a). More detailed calculations show that the two definitions are consistent with each other in every respect. In the process of developing these ideas, we shall also deepen our understanding of what we mean by disorder. ... 

It is known that the use of this type of sub-microscopic explanatory model is very challenging to matty learners (Harrison Treagust, 2002). Indeed, failing to fully appreciate the way quanticles have different properties to famihar particles, students cotranonly adopt a type of pseudo-explanation where they explain the properties of bulk matter in terms of the properties to be explained being properties of the atoms or molecules of which the bulk material is composed. This is represented in Fig. 4.4 which illustrates the tautological nature of these kinds of pseudo-explanations they can only explain the properties if we just accept that the qrranticles have these very properties. 

Physics and chemistry of nanosized species have been the focus of attention of scientists for the last three decades. During this period of time even the name of this field of science has changed. Initially, the science has been dealing with ultra-dispersed particles. Later on, the scale of the species under study has been restricted to nanodimension. In fact, the properties of particles within this dimension of sizes differ from the both atoms (molecules) and bulk matter. The worldwide revolutionary developments in the science of nanosized particles became possible because of the efforts of physicists, chemists, biologists, experts in material science, and theoreticians. Later on, this field of science attracted the attention of the representatives of such fields like ethics and economy. 

In bulk matter the quark-hadron mixed phase begins at the static transition point defined according to the Gibbs criterion for phase equilibrium... 

The phase relations among the scattered wavelets depend on geometrical factors scattering direction, size, and shape. But the amplitude and phase of the induced dipole moment for a given frequency depend on the material of which the particle js composed. Thus, for a full understanding of scattering und absorption by small particles, we need to know how bulk matter responds to oscillatory electromagnetic fields this is the subject of Chapters 9 and 10. 

An excellent concise treatment of scattering—by molecules and particles, single and multiple—at an intermediate level is Chapter 14 of Stone (1963). Among the books devoted entirely to scattering by particles, that by Shifrin (1951) most closely resembles ours in that it discusses optical properties of bulk matter as well. Biit the two books that have influenced us most are those of van de Hulst (1957) and Kerker (1969) we are indebted to both authors. Another book on scattering, which emphasizes polydispersions, is by Deirmendjian (1969). 

The considerations in the preceding section make it worthwhile to discuss reflection and transmission at plane boundaries first, one plane boundary separating infinite media, then in the next section two successive plane boundaries forming a slab. In addition to providing useful results for bulk materials, these relatively simple boundary-value problems illustrate methods used in more complicated small-particle problems. Also, the optical properties of slabs often will be compared to those of small particles—both similarities and differences—to develop intuitive thinking about particles by way of the more familiar properties of bulk matter. 

There is one important idea, the raison d etre of this book, that we should like to implant firmly in the minds of our readers scattering theory divorced from the optical properties of bulk matter is incomplete. Solving boundary-value problems in electromagnetic theory may be great fun and often requires considerable skill but the full physical ramifications of mathematical solutions are hidden to those with little knowledge of how refractive indices of various solids and liquids depend on frequency, the values they take, and the constraints imposed on them. Accordingly, this book is divided into three parts. 

Bulk matter, rather than particles, is the subject of Part 2. In Chapter 9 we discuss classical theories of optical properties based on idealized models. Such models rarely conform strictly to reality, however, so Chapter 10 presents measurements for three representative materials over a wide range of frequencies, from radio to ultraviolet aluminum, a metal magnesium oxide, an insulator and water, a liquid. 

Lasers come next, not because of their intrinsic construction and mode of operation, but because they open up new dimensions of technique, precision, and scale. The experimental technique of physical chemistry that has benefited most from the laser is Raman spectroscopy, which barely existed before their introduction and is now in full flower, showing enormously detailed and interesting information about bulk matter and surfaces. A technique that was essentially invented by the laser is femtochemistry, where we can catch atoms red-handed in the act of reaction. Lasers have brought us right to the heart of reactions, and as such we must build them into our courses. 

As we see in the rest of the book, many of the interesting properties of colloids are the result of their dimension, which lies between atomic dimensions and bulk dimensions. Two of the important consequences of the size range of colloids are (a) colloidal materials have enormous surface areas and surface energies, and (b) the properties of colloidal particles are not always those of the corresponding bulk matter or those of the corresponding atoms or molecules. Let us use a simple exercise or a thought experiment to illustrate these points. 

The preceding section shows that it is possible to determine tt-A isotherms for surfaces just as p- V isotherms may be measured for bulk matter. The results that are obtained for surfaces are analogous to bulk observations also, although some caution must be expressed about an overly literal correlation between bulk and surface phenomena. We return to a discussion of these reservations below. There can be no doubt, however, that analogies with bulk behavior supply a familiar framework within which to consider tt-A isotherms. 

NMR transitions were first observed by Rabi and co-workers in 1938, using a molecular-beam apparatus.3 NMR transitions in bulk matter were first detected in 1945 by two independent groups, one headed by Bloch, the other by Purcell these two men shared the 1952 Nobel physics prize.4... 

We now consider NMR transitions in bulk matter. The sample can be a solid, liquid, or gas. Comparatively little gas-phase work has been done, due to the weakness of the absorption signal. NMR in solids will be considered separately in Section 8.7. The most common application of NMR is to liquid samples. 

The science of materials may have begun in the blacksmith s forge, but the materials of tomorrow will be formulated by understanding how the properties of matter are determined by the arrangements of its atoms and molecules. Scientists understand and invent new materials by considering the properties and interactions of individual particles and predicting how those properties translate into bulk properties. This chapter continues the important task of relating atomic and molecular properties to the structure and properties of bulk matter. 

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