Laves principles

For crystal symmetry analysis, inorganics can be divided into two compounds of ternary and higher oxides and compounds containing halides and noble gases are classed as inorganics, and the remainder are classed as intermetallics. One of Laves principles states that structures aim at the highest symmetry. Figure 2 shows the distribution of compounds by crystal system. ... 

Whereas the Mg atoms are in contact with each other and the Cu atoms are in contact with each other, the Cu partial structure floats inside the Mg partial structure. The hard sphere model proves to be insufficient to account for the real situation atoms are not really hard. The principle of the most efficient filling space should rather be stated as the principle of achieving the highest possible density. Indeed, this shows up in the actual densities of the Laves phases they are greater than the densities of the components (in some cases up to 50 % more). For example, the density of MgCu2 is 5.75 g cm-3, which is 1% more than the mean density of 5.37 g cm-3 for 1 mole Mg + 2 moles Cu. Therefore,... 

In crystalline solids a tendency to form arrangements of high symmetry is observable. The symmetry principle, put forward in this form by F. Laves, has been stated in a more exact manner by H. Barnighausen ... 

The results of these analyses can be compared with the Stability Principles stated by Laves ( 4.3.2.5). 

Geometrical considerations about intermetallic crystal structures. When discussing the factors which control the structures of the metallic elements, Laves (1956) proposed three interrelated principles that are mainly geometric in character and also related to the atomic dimensional characteristics ... 

The principle of highest symmetry (symmetry principle). According to Laves, a tendency to build configurations with high symmetry is evident. This tendency is particularly clear in metallic structures, especially in the simple ones. 

Under any conception of legal necessity, one principle is clear The defense cannot succeed when the legislature itself has made a determination of values. 1 W. La lave A. Scott, Substantive Criminal Law 5.4, p. 629 (1986). In the case of the Controlled Substances Act, the statute reflects a determination that marijuana has no medical benefits worthy of an exception (outside the confines of a Government-approved research project). Whereas some other drugs can be dispensed and prescribed for medical use, see 21 U.S.C. 829 the same is not true for marijuana. Indeed, for purposes of the Controlled Substances Act, marijuana has no currently accepted medical use at all. 811. 

Without laving too much stress upon the most modern view, that of regarding electricity atomically by moans of the idea of electrons, all known phenomena justify us in dealing with positive and negative electrical quantities as with chemically active masses, and applying to them the principles of reaction kinetics. 

The connection principle leads to the occurrence of atom groups with the shortest interatomic contacts referred to as connections according to Laves Owing to the ability of chemical bonds to be coordinated in certain directions, these connections may be finite formations which are called groups and islands, respectively (see Sect. 3). Onedimensional, two-dimensional and three-dimensional infinite connections are called chains, layers and skeletons, respectively. 

Figure 1 Schematic drawing of the various ways in which metal ions can, in principle, facilitate hydrolysis of a phosphate ester by providing a coordinated nucleophile, activating the substrate and stabilizing the transition state, and stabilizing the laving group. Similar factors are operative for hydrolysis of amide bonds.

The formulation of the Principles of Laves - explains the spatial occupation in crystalline structures. 

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