Electron Configuration and Chemistry

The electron configuration for the lanthanides and the two preceding and two following elements are shown in Table 17.12. 

No Croup Element Shell 1 K Shell 2L Shell 3 M Shell 4N Shell 50 Shell 6P 

For all lanthanides the outermost shell 6 (K) has 2 s-electrons and the number of 5d-electrons is also formally the same, namely 1, in all the elements. That is the background to the chemical similarity between the different lanthanides and the very hard separation and discovery work, described above. The picture is, however, not quite so simple. The energy of the sole 5d-electron within the lanthanide atoms is almost the same as for the 4f-electrons. Spectroscopic examination indicates a modified electronic configuration as shown in Table 17.13 [17.11]. 

Several lanthanide ions have a characteristic color in water solutions, as shown in Table 17.14. The color for an element ion with n f-electrons is very similar to those element ions that have (14 - n) electrons. In the table the colors of powdered common oxides are shown. 

Atomic Number Element Ion Color Number of felectrons Oxide  

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