Quantum Theory and the Electronic Structure of Atoms

Lasers are used in a variety of surgical procedures, including cosmetic procedures. LASIK surgery, shown here, is done to improve eyesight. 

Student Annotation LASIK is an acronym for LASer-assisted In situ Keratomileusis. 

At the end of this chapter, you will be able to answer a variety of questions about the nature of light and the electronic structure of the atom. [ page 247] 

About some of the properties of electromagnetic radiation or light and how these properties have been used to study and elucidate the electronic structure of atoms. You will also learn how to determine the arrangement of electrons in a particular atom. 

CHAPTER 6 Quantum Theory and the Electronic Structure of Atoms 

The answers to these questions have a direct relationship to the behavior of all substances in chemical reactions, and the story of the search for answers provides a fascinating backdrop for our discussion. 

Early attempts by nineteenth-century physicists to understand atoms and molecules met with only limited success. By assuming that molecules behave like rebounding balls, physicists were able to predict and explain some macroscopic phenomena, such as the pressure exerted by a gas. However, this model did not account for the stability of molecules that is, it could not explain the forces that hold atoms together. It took a long time to reahze— and an even longer time to accept—that the properties of atoms and molecules are not governed by the same physical laws as larger objects. 

The new era in physics started in 1900 with a young German physicist named Max Planck. While analyzing the data on radiation emitted by solids heated to various temperatures, Planck discovered that atoms and molecules emit energy only in certain discrete quantities, or quanta. Physicists had always assumed that energy is continuous and that any amount of energy could be released in a radiation process. Planck s quantum theory turned physics upside down. Indeed, the flurry of research that ensued altered our concept of nature forever. 

Another important property of waves is their speed, which depends on the type of wave and the nature of the medium through which the wave is traveling (for example, air, water, or a vacuum). The speed (u) of a wave is the product of its wavelength and its frequency  

The inherent sensibility of Equation (7.1) becomes apparent if we analyze the physical dimensions involved in the three terms. The wavelength (X) expresses the length of a wave, or distance/wave. The frequency (v) indicates the number of these waves that pass any reference point per unit of time, or waves/time. Thus, the product of these terms results in dimensions of distance/time, which is speed  

Before you begin, you should review Media Player/ 

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CHAPTER 7 QUANTUM THEORY AND THE ELECTRONIC STRUCTURE OF ATOMS... 

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