Electron Configurations in Atoms

Given the rules referred to in Section 6.3, it is possible to assign quantum numbers to each electron in an atom. Beyond that, electrons can be assigned to specific principal levels, sub-levels, and orbitals. There are several ways to do this. Perhaps the simplest way to describe the arrangement of electrons in an atom is to give its electron configuration, which shows the number of electrons, indicated by a superscript, in each sublevel For example, a species with the electron configuration 

In this section, you will learn how to predict the electron configurations of atoms of elements. There are a couple of different ways of doing this, which we consider in turn. It should be emphasized that, throughout this discussion, we refer to isolated gaseous atoms in the ground state. (In excited states, one or more electrons are promoted to a higher energy level) 

Click Coached Problems for a self-study module on shapes of atomic orbitals. 

These are ground-state configurations 1s22s 2p2 would be an excited state for boron. 

The order shown is the order of sublevel filling as atomic number increases, starting at the bottom with Is, 

Beyond neon, electrons enter the third principal level. The 3s sublevel is filled at magnesium  

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Formal charges can be used to help in the assessment of resonance structures and molecular topology. The use of formal charges is presented here as a simplified method of describing structures, just as the Bohr atom is a simple method of describing electronic configurations in atoms. Both of these methods are incomplete and newer approaches are more accurate, but they can be useful as long as their limitations are kept in mind. 

Quantum mechanics olecular modeling method that examines the electronic structure and energy of molecular systems based on various schemes for solving the Schrodinger equation based on the quantized nature of electronic configurations in atomic and molecular orbitals. 

Some of the important properties of solid materials depend on geometrie atomie arrangements and also the interactions that exist among constituent atoms or molecules. This chapter, by way of preparation for subsequent discussions, considers several fundamental and important concepts—namely, atomic structure, electron configurations in atoms and the periodic table, and the various types of primary and secondary interatomic bonds that hold together the atoms that compose a solid. These topics are reviewed briefly, under the assumption that some of the material is familiar to the reader. 

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