Our Atomic World

Eldred C. Nelson and Leonard 1. Schiff, Our Atomic World (Albuquerque University of New Mexico Press, 1945). Dexter Masters and Katherine Way, eds.. One World or None (New York McGraw-Hill, 1946). Russell R. Williams, "The Atomic Age," Saturday Review, December 1, 1945. David Dietz, Atomic Energy in the Coming Era (New York Dodd Mead,... 

The Atomic Bomb," January 10, 1946, transcript (published February 15, 1946) copy given by Tim Moy and in author s possession. Philip Morrison, "If the Bomb Gets Out of Hand," in Masters and Way, One World or None (New York McGraw-Hill, 1946), 6. Louis N. Ridenour, "There Is No Defense," in Masters and Way, One World or None, 33. Nelson and Schiff, Our Atomic World, 6. Federation of American (Atomic) Scientists, "Survival Is at Stake," in Masters and Way, One World or None, 78 Lewis Mumford, "Gentlemen You Are Mad " Saturday Review of Literature 29 (March 2, 1946) 8. 

Enrico Fermi, foreword to Nelson and Schiff, Our Atomic World, 3. Nelson and Schiff, Our Atomic World, 49, 53. Harold C. Uery, "How Does It All Add Up In Masters and Way, One World or None, 55. 

Nelson, Eldred C., and Leonard I. Schiff, eds. Our Atomic World. Albuquerque University of New Mexico Press, 1946. 

There are many other examples of interrelationship. Symmetry, for example, is of fundamental importance in the sciences and arts alike. It plays a key role in our understanding of the atomic world as well as the cosmos. The handedness of molecules, with nature selecting one... 

A sutmnaty of the above shows various terms used for eaeh type of representation first (maero level, maeroscopic level, macroscopic world), second (sub-micro level, microscopic level, submicro level, submicroscopic level, molecular world, atomic world), and third (symbolic level, sy mbolic world, representational chemistry, algebraic system). In onr view, the system of terminology shonld be both as brief as possible and avoid any possible ambiguities of meaning. Conseqnently, sub-micro and snb-microscopic fall foul of our first criterion for they perhaps imply that snch a level can be seen through an optical microscope. For those reasons, we have decided to nse macro, submicro, symbolic for the individual types and triplet relationship to cover all three. The triplet relationship is a key model for chemical edncation. However, the authors in this book have been fiee to decide for themselves which conventions to use. Nevertheless, it is our intention to promote the terms macro, submicro, symbolic in all subsequent work and to discuss the value of the triplet relationship in chemical education. 

The units we use in daily life, such as kilogram (or pound) and meter (or inch) are tailored to the human scale. In the world of quantum mechanics, however, these units would lead to inconvenient numbers. For example, the mass of the electron is 9.1095 X J0 31 kg and the radius of the first circular orbit of the hydrogen atom in Bohr s theory, the Bohr radius, is 5.2918 X 10 11 m. Atomic units, usually abbreviated as au, are introduced to eliminate the need to work with these awkward numbers, which result from the arbitrary units of our macroscopic world. The atomic unit of length is equal to the length of the Bohr radius, that is, 5.2918 X 10 n m, and is called the bohr. Thus 1 bohr = 5.2918 X 10"11 m. The atomic unit of mass is the rest mass of the electron, and the atomic unit of charge is the charge of an electron. Atomic units for these and some other quantities and their values in SI units are summarized in the accompanying table. 

In using this book my hope is that the reader will realize that chemistry and chemical compounds are much more than atoms and bonds indeed, chemical compounds, like people, are unique individuals. Millions of chemical compounds exist, with thousands of new compounds formed daily. Each of these compounds is unique, but collectively they shape our physical world. The 100 Most Important Chemical Compounds introduces the reader to the most notable of these compounds. I hope the book will stimulate interest in knowing more. 

The term "superheavy elements" was first coined for elements on a remote "island of stability" around atomic number 114 (Chapter 8). At that time this island of stability was believed to be surrounded by a "sea of instability". By now, as shown in Chapter 1, this sea has drained off and sandbanks and rocky footpaths, paved with cobblestones of shell-stabilized deformed nuclei, are connecting the region of shell-stabilized spherical nuclei around element 114 to our known world. 

This book concerns the common atoms of our natural world. How many of each element exist, and why What variations are found in the relative numbers of the isotopes of each element, and how are those variations interpreted If I could write an epic poem, I would lyricize over the history of the universe writ small by their natural abundances. I would rhapsodize over the puzzling arrangements at different times and places of the thousand or so different isotopes of some ninety chemical elements. These different arrangements speak of distant past events. 

What became apparent was that the failures of the two theories and the ways they were amended had something in common. The simple theories did not initially incorporate all the dimensions that were part of our real world. Especially, noteworthy was the fact that neither had incorporated the evolutionary perspective, time s arrow, by which we who live in the 21st century make sense of large areas of the sciences and their interconnections. Structural theory in fact ignored time completely. Also neither theory in its classic form took account of the fact that atoms, molecules, and chemical bonds required space to exist, they were not points. Those were two crucial omissions. 

The truth is that both matter and energy show both behaviors each possesses both faces. In some experiments, we observe one face in other experiments, we observe the other face. The distinction between a particle and a wave is meaningful only in the macroscopic world, not in the atomic world. The distinction between matter and energy is in our minds and our limiting definitions, not inherent in nature. This dual character of matter and energy is known as the wave-particle duality. 

This all too human attempt by Mendeleev to cram the ether concept into his Periodic Table illustrates our very human limitations in trying to fit our own world views to facts. Figure 306 depicts mid-nineteenth-century illustrations of dinosaurs. The bones were crammed into the shapes of bear-like or ox-like creatures because these were the largest land carnivores and herbivores then known. Indeed, the planetary model of the atom, developed by Bohr in 1913 and later completely eclipsed, was probably based upon his desire for a unity in the universe and an analogy with the solar system. 

What exactly is molecular mechanics It is the study of the interaetions of non covalently bonded atoms in one or more molecules which determine the spatial eonforma-tion of such a structure or its change of conformation induced by a neighboring moleeule. In short, it is the modeling of the structures of molecules, their struetural interaetions and modifications, and hence of their macroscopic and microscopic properties derived from the molecular level according to first principles in physics and physical chemistry. Its mundane appearanee is that of a computational technique, and today extensive eomputa-tion is always included. However, it is indeed much more than just a eomputational technique it is the technique par excellence to explain our physieal world from first, molecular, and atomic principles. 

The science of thermodynamics developed as a means of describing the properties of matter in our macroscopic world without regard to microscopic structure. In fact, thermodynamics was a well-developed field before the modern view of atomic and molecular structure was even known. The thermodynamic properties of water, for example, addressed the behavior of bulk water (or ice or water vapor) as a substance without considering any specific properties of individual H2O molecules. 

Yet, currently there is much interest in field theories in many dimensions, which picture our physical world as resulting from com-pactification of a higher dimensional space [5]. Also, atoms and molecules can be reduced to quasi-one-dimensional structures by the huge magnetic field of a neutron star or pulsar [6]. Without resort to such exotic realms, good approximations to D > 3 atoms exist. The U = 5 case, and others of higher odd-Z>, actually occur as doubly-excited states of two-electron atoms, as described in several portions of this book. The D = 2 case is exemplifed, e.g., in impurity states in quantum well systems [7], of practical interest for electronic devices. 

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