Quantum mechanical model configuration

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. 

The quantum mechanical model and the electron configurations of the elements provide the basis for explaining many aspects of chemistry. Particularly important are the electrons in the outermost orbital of... 

By modifying the classical theory and using a quantum-mechanical model for the critically activated complex it is possible to extend the detailed theory [Eqs. (XI.8.3) and (XI.8.3a)] in such a way as to include consideration of structural changes on the internal frequencies. In Eq. (XI.8.3) V represents a weighted average of the internal fre(i[uencies of a species that has the configuration of the transition state and represents the equilibrium constant for the equilibrium between this transition state and normal molecules. and respectively represent the standard... 

The essence of the periodic table is that members of each group of representative elements exhibit similar chemical properties that change in a regular way. The quantum mechanical model has allowed us to understand that the similarity of properties of the atoms in a group arises from the identical valence electron configurations shared by group members. It is the number and type of valence electrons that primarily determine an atom s chemistry. 

Another similarity of MO theory to the quantum-mechanical model for atoms is that we can write electron configurations for a molecule. The symbol of each occupied MO is shown in parentheses, and the number of electrons in it is written outside as a superscript. Thus, the electron configuration of H2 is (ct,.). ... 

The results considered in this section are very important. We have seen that the quantum mechanical model can be used to explain the arrangement of the elements in the periodic table. This model allows us to understand that the similar chemistry exhibited by the members of a given group arises from the fact that they all have the same valence electron configuration. Only the principal quantum number of the valence orbitals changes in going down a particular group. 

Another conclusion we can draw is that if we are in a situation where two or more electronic configurations (of the same symmetry) have the same or almost the same energy, they will mix strongly and a quantum-mechanical model that takes only one of them into account will not be valid. 

The Quantum-Mechanical Model and the Periodic Table Bulding Up Periods 1 and 2 Buiding Up Period 3 Section Configurations Within Groups Building Up Period 4... 

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