Metallic radii. 178-9

An equation has been formulated to express the change in covalent radius (metallic radius) of an atom with change in bond number (or in coordination number, if the valence remains constant), the stabilizing (bond-shortening) effect of the resonance of shared-electron-pair bonds among alternative positions being also taken into consideration. This equation has been applied to the empirical interatomic-distance data for the elementary metals to obtain a nearly complete set of single-bond radii. These radii have been compared with the normal covalent... 

Fig. 19. The variation in logK for alkali metal ions with crown ethers 12-crown-4 (3), 15-crown-5 (O), 18-crown-6 ( ) and dibenzo-30-crown-10 (C) as a function of metal ion radius. Metal ion radii in A from Ref. (20). Formation constants in methanol from Refs. (49 and 50).

At low adsorbate coverages the surface structure of the deposited metal is determined by the substrate periodicity. Thus, under these conditions the adsorbate-substrate interaction is predominant. At higher coverages the adsorbate may continue to follow the substrate periodicity or form coincidence structures with new periodicities that are unrelated to the substrate periodicity. The ordering geometry of large-radius metallic adatoms (especially K, Rb and Cs) shows relatively little dependence on the substrate lattice they tend to form hexagonal close-packed layers on any metal... 

Decreases all the way across atomic radius, metallic character, ionic character of halides, alkalinity of oxides... 

In order to better estimate the effect of the water, a comparison calculation for a 2 region system consisting of a 1.25 cm radius metal cylinder concentric with an 11.1 cm radius graphite cylinder has been carried out. The distributions at thermal and resonance energies are shown in the figures. The thermal utilization factor, for such an arrangement is 1.185, the resonance absorption factor, is 1.100 and so n = x - = 1.304. 

I Mass ratio Mass ratio Covalent radius Metallic radius, CN = 12 van der Waals radius... 

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