Electron Configuration and Ionization Energy of Neutral Atoms in the

Electron Configuration and Ionization Energy of Neutral Atoms in the Groimd State... 

Extensive studies of energy spectra and other characteristics of atoms and ions allow one to reveal general regularities in their structure and properties [255-257]. For example, by considering the lowest electronic configurations of neutral atoms, we can explain not only the structure of the Periodical Table of elements, but also the anomalies. The behaviour of the ionization energy of the outer electrons of an atom illustrates a shell structure of electronic configurations. 

Table 8.1 lists some key physical properties of the elements of the first transition series, taken mostly from Appendix F. The general trends in all of these properties can be understood by recalling that nuclear charge also increases across a period as electrons are being added to the same subshell, in this case, the d shell. The first and second ionization energies tend to increase across the period, but not smoothly. The energies of the 4s and 3d orbitals are so close to one another that the electron configurations of the neutral atoms and their ions are not easily predicted from the simplest model of atomic structure. 

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