The arrangement of electrons in atoms

For many purposes, electron configurations are sufficient to describe the arrangements of electrons in atoms. Sometimes, however, it is useful to go a step further and show how electrons are distributed among orbitals. In such cases, orbital diagrams are used. Each orbital is represented by parentheses (), and electrons are shown by arrows written f or, depending on spin. 

In this chapter, a brief review of quantum mechanical methods and the arrangement of electrons in atoms has been presented. These topics form the basis for understanding how quantum mechanics is applied to problems in molecular structure and the chemical behavior of the elements. The properties of atoms discussed in Chapter 1 are directly related to how the electrons are arranged in atoms. Although the presentation in this chapter is not exhaustive, it provides an adequate basis for the study of topics in inorganic chemistry. Further details can be found in the references. 

Electron configuration The arrangement of electrons in atomic orbitals. 

Irving Langmuir, "The Arrangement of Electrons in Atoms and Molecules," JACS 41 (1919) 868934 and "Isomorphism, Isoterism and Covalence," JACS 41 (1919) 15431559 also, "The Structure of Molecules,"... 

I. Langmuir, The arrangement of electrons in atoms and molecules, Journal of the American Chemical Society 41 (1919) 868-934 Isomorphism, isoterism and covalence, ibid., 1543-1559 The Structure of Molecules, BAAS Reports, 1921, Edinburgh (London, 1922), 468-469. 

In what ways are periodic trends related to the arrangement of electrons in atoms ... 

You will express the arrangements of electrons in atoms through orbital notations, electron configurations, and electron dot structures. 

When you consider that atoms of the heaviest elements contain in excess of 100 electrons, that there are numerous principal energy levels and sublevels and their corresponding orbitals, and that each orbital may contain a maximum of two electrons, the idea of determining the arrangement of an atom s electrons seems daunting. Fortunately, the arrangement of electrons in atoms follows a few very specific rules. In this section, you ll learn these rules and their occasional exceptions. 

Our ideas about the arrangements of electrons in atoms have evolved slowly. Much of the information has been derived from atomic emission spectra. These are the lines, or bands, produced on photographic film by radiation that has passed through a refracting glass prism after being emitted from electrically or thermally excited atoms. To help us understand the nature of atomic spectra, we first describe electromagnetic radiation. 

Observing the Trend Many natural phenomena, such as the increasing spiral of a Nautilus shell and, as you ll see in this chapter, the arrangement of electrons in atoms, recur with such periodic regularity that they allow us to predict properties and behavior. 

Armed with knowledge of the relative energies of orbitals and the PauH exclusion principle, we are in a position to consider the arrangements of electrons in atoms. The way electrons are distributed among the various orbitals of an atom is called the electron configuration of the atom. 

In Section 1.5, it was noted that electrons form a cloud of negative charge around the nucleus of an atom. The energy levels, orientations in space, and behavior of electrons vary with the numbm of them contained in an atom. In a gen al sense, the arrangements of electrons in atoms are described by electron configuration, a term discussed in some detail later in this chapter. 

C.R. Bury, Langmuir s Theory of the Arrangement of Electrons in Atoms and Molecules Journal of the American Chemical Society, 43,1602-1609,1921, table from p. 1603. 

Langmuir I (1919) The arrangement of electrons in atoms and molecules. J Am Chem Soc... 

In later chapters we will study some chemical reactions of elements and their compounds and relate the reactions to the locations of the elements in the periodic table. First, we will describe the arrangements of electrons in atoms. A knowledge of these arrangements not only provides the physical basis for the periodic table, but also explains chemical bonding and properties. 

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