Quantum mechanics, atomic structure electron configurations

An atom consists of a positively charged nucleus surrounded by one or more negatively charged electrons. The electronic structure of an atom can be described by a quantum mechanical wave equation, in which electrons are considered to occupy orbitals around the nucleus. Different orbitals have different energy levels and different shapes. For example, s orbitals are spherical and p orbitals are dumbbell-shaped. The ground-state electron configuration of an... 

In this chapter, you learned about the electronic structure of the atom in terms of the older Bohr model and the newer quantum mechanical model. You learned about the wave properties of matter, and how to describe each individual electron in terms of its four quantum numbers. You then learned how to write the electron configuration of an atom and some exceptions to the general rules. 

In this section, you have seen how a theoretical idea, the quantum mechanical model of the atom, explains the experimentally determined structure of the periodic table, and the properties of its elements. Your understanding of the four quantum numbers enabled you to write electron configurations and draw orbital diagrams for atoms of the elements. You also learned how to read the periodic table to deduce the electron configuration of any element. 

We may now ask why the valence of tin in the metallic form of the element is not 2, corresponding to one metallic orbital per atom and the electron configuration 4d °5 J5pt, but is 2.56. The answer is, I think, given by the quantum-mechanical principle that the actual structure for the normal state of a system is that structure, from among all... 

Atomic structure is fundamental to inorganic chemistry, perhaps more so even than organic chemistry because or the variety or elements and their electron configurations that must be dealt with. It will be assumed that readers will have brought with them from earlier courses some knowledge oT quantum mechanical concepts such as the wave equation, the particle-in-a-box. and atomic spectroscopy. 

The modern view of the periodic table explains its structure in terms of an Aufbau procedure based on the wave-mechanical model of the hydrogen atom. Although seductive at first glance, the model is totally inadequate to account for details of the observed electronic configurations of atoms, and makes no distinction between isotopes of the same element. The attractive part of the wave-mechanical model is that it predicts a periodic sequence of electronic configurations readily specified as a function of atomic number. The periodicity follows from the progressive increase of four quantum numbers n, l, mi and s, such that... 

Quantum mechanics has shown that periodicity is conditioned by the repetition of the configurations of outer electrons and it is natural that only those properties which are concerned with the structure of the outer electrons of the atoms should reveal periodicity. Thus it is found that ionization potentials, ionic dimensions, polarisation etc when considered as a function of atomic number give a curve similar to the atomic volume curve. Other... 

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