Inner-shell electrons

Dalton s atomic theory Electron shells Inner shell electrons Octet rule... 

The electron configuration is the orbital description of the locations of the electrons in an unexcited atom. Using principles of physics, chemists can predict how atoms will react based upon the electron configuration. They can predict properties such as stability, boiling point, and conductivity. Typically, only the outermost electron shells matter in chemistry, so we truncate the inner electron shell notation by replacing the long-hand orbital description with the symbol for a noble gas in brackets. This method of notation vastly simplifies the description for large molecules. 

When the hole in the /th shell is filled by an electron from theyth shell, there is a hole in the latter shell that will in turn be filled by an electron from a higher kth shell. This may result in the emission of a second x-ray, such that one hole in an inner electron shell can result in a cascade of several x-rays having ever-decreasing energies. 

The molal diamagnetic susceptibilities of rare gas atoms and a number of monatomic ions obtained by the use of equation (34) are given in Table IV. The values for the hydrogen-like atoms and ions are accurate, since here the screening constant is zero. It was found necessary to take into consideration in all cases except the neon (and helium) structure not only the outermost electron shell but also the next inner shell, whose contribution is for argon 5 per cent., for krypton 12 per cent., and for xenon 20 per cent, of the total. 

The atomic number of an atom equals the number of protons in the nucleus and thus the positive charge of the nucleus. The effective nuclear charge is the positive charge experienced by the outermost electrons. Intervening electrons of inner shells cancel much of the nuclear charge out. 

We discuss briefly the factors that determine the intensity of the scattered ions. During collision, a low energy ion does not penetrate the target atom as deeply as in RBS. As a consequence, the ion feels the attenuated repulsion by the positive nucleus of the target atom, because the electrons screen it. In fact, in a head-on collision with Cu, a He+ ion would need to have about 100 keV energy to penetrate within the inner electron shell (the K or Is shell). An approximately correct potential for the interaction is the following modified Coulomb potential [lj ... 

This chapter discusses the range of analytical methods which use the properties of X-rays to identify composition. The methods fall into two distinct groups those which study X-rays produced by the atoms to chemically identify the elements present, and X-ray diffraction (XRD), which uses X-rays of known wavelengths to determine the spacing in crystalline structures and therefore identify chemical compounds. The first group includes a variety of methods to identify the elements present, all of which examine the X-rays produced when vacancies in the inner electron shells are filled. These methods vary in how the primary vacancies in the inner electron shell are created. X-ray fluorescence (XRF) uses an X-ray beam to create inner shell vacancies analytical electron microscopy uses electrons, and particle (or proton) induced X-ray emission (PIXE) uses a proton beam. More detailed information on the techniques described here can be found in Ewing (1985, 1997) and Fifield and Kealey (2000). 

Protons can also be used instead of X-rays or electrons to create the initial vacancies in the inner electron shells, giving rise to a method known as proton induced X-ray emission (PIXE). In these instruments a high intensity, highly focused beam of protons is produced by a van de Graaff accelerator,... 

X-ray tube—A metal anode is bombarded with high-energy electrons causing inner-shell electrons to be ejected and replaced by higher shell electrons. The loss in energy of these electrons as they drop to the lower levels is on the order of the energy of x-rays, and x-rays are emitted. 

It should be noted that the experimental set of structure amplitudes for Ge was obtained up to sinOA = 1.72 A. This allowed not only to refine more exactly the scale and temperature factors but also provided high resolution in the electron density, the ESP maps and the Laplacian of the electron density. For example the inner electron shells of the core in Ge can be seen in figure 11. 

Due to the presence of the several electron shells, a series of different X-lay lines are produced in cascades following inner shell ionizations. Notation of the lines corresponds to historical reasons (a is the strongest, P is the next strongest, etc.) and (in case of some minor lines) it is not always logical. The... 

Free valencies of such an exciton nature may be significant in semiconductors, one component of which is a transition metal possessing an unfilled inner electron shell or a shell that can easily give up an electron. This may, perhaps, explain certain specific catalytic properties of such semiconductors. However, the role of Frenkel excitons in the phenomena of chemisorption and catalysis has been as yet investigated to a very small extent, and in the following we shall not consider free valencies of such an exciton origin. 

A familiar way of handling this question is offered by the notion of electronic shells. By definition, an electronic shell collects all the electrons with the same principal quantum number. The K shell, for example, consists of U electrons, the L shell collects the 2s and 2p electrons, and so on. The valence shell thus consists of the last occupied electronic shell, while the core consists of all the inner shells. This segregation into electronic shells is justified by the well-known order of the successive ionization potentials of the atoms. 

The colors in rare earth glasses are caused by the ion being dissolved and they behave uniquely because the 4 f electrons are deeply buried. Their colors depend on transitions taking place in an inner electronic shell while in other elements such as the transition metals, the chemical forces are restricted to deformation and exchanges of electrons within the outer shell. Since the rare earth s sharp absorption spectra are insensitive to glass composition and oxidation-reduction conditions, it is easy to produce and maintain definite colors in the glass making process. ( )... 

Thus, according to these calculations the formation of the hydrogen bond is accounted for by the decrease of repulsion between A—H and B and by the presence of some donor-acceptor interaction H B besides by the purely electrostatic interaction. It is found that the peculiarity of the hydrogen atom in the formation of interxnoleeular (or intramolecular) bonds is, first, that it has no inner electron shell and second, that it has rather high an ionization potential. 

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