Electron Configurations Within Groups

Building Up Period 3 251 Similar Electron Configurations Within Groups 252... 

A valuable aspect of the arrangment of atoms on the basis of similar electronic configurations within the periodic table is that an atom s position provides information about its properties. Some of these properties, and how they vary across periods and groups, are now discussed. 

Figure 8.9 shows a paiodic table with the valence-shell configurations included. Note the similarity in electron configuration within any group (column) of elements. This similarity explains what chemists since Mendeleev have known—the properties of elements in any group are similar. 

To construct Table 8.3, we have taken three groups of elements from the periodic table and written their electron configurations. The similarity in electron configuration within each group is readily apparent. If the shell of the highest principal quantum number—the outermost, or valence, shell—is labeled n, then... 

This quantity is proportional to the magnetic field at the nucleus due to the unpaired s-electron configurations of the ion and is constant within 20% for ions of the iron group, if covalent bonding is not extreme as in cyanides of Mn in ZnS. 

A 3H and 2H NMR study of single crystals of [Ag(NH3)2][Ag(ONO)2] has been reported.32 Rapid reorientational motions of the ammine groups around their C3 axes were found. The orientations of the C3 axes within the crystal corresponded with the Ag—N bond directions of the [H3N—Ag—NH3]+ unit. The deuterium quadrupole coupling constant was determined and found to be identical to that of solid ND3. It was concluded that the electronic configuration and the geometric structure of ammonia were changed only very slightly upon coordination to silver ions. 

Trends in ionization energy and electron affinity within a period reflect the stability of valence electron configurations. A stable system requires more energy to change and releases less when changed. Note the peaks in stability for groups 2, 13, and 16. 

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