Electronegativity and atomic size

From Tsai s pioneering discoveries [25,27], we know that atomic size, electronegativity, and valence electron counts play substantial roles in the formation of QCs. These criteria are expressed by the Hume-Rothery rules [30,31]. However, three additional highlights are also important in the consideration of possible candidate systems, at least from the viewpoint of chemists. 

Complete solid solubility requires that components have the same crystal structure, similar atomic size, electronegativity and valency. If any of these conditions are not met, a miscibility gap will occur in the solid state. 

Transition metals share properties such as electrical conductivity, luster, and malleability with other metals. There is little variation in atomic size, electronegativity, and ionization energy across a period. However, there are differences in properties among these elements, especially physical properties. For example, silver is the best conductor of electricity. Iron and titanium are used as structural materials because of their relative strength. 

Trends Across a Period Consider the variations in atomic size, electronegativity, and ionization energy across Period 4 (Figure 22.3) ... 

The difference in atomic size, electronegativity and the crystal orientation determines the manner of tetrahedron orientation and the patterns of reconstruction. 

Line compounds. These are phases where sublattice occupation is restricted by particular combinations of atomic size, electronegativity, etc., and there is a well-defined stoichiometry with respect to the components. Many examples occur in transition metal borides and silicides, III-V compounds and a number of carbides. Although such phases are considered to be stoichiometric in the relevant binary systems, they can have partial or complete solubility of other components with preferential substitution for one of the binary elements. This can be demonstrated for the case of a compound such as the orthorhombic Cr2B-type boride which exists in a number or refractory metal-boride phase diagrams. Mixing then occurs by substitution on the metal sublattice. 

Stolten has developed a semi-empirical estimation method to obtain enthalpies of formation of carbides, nitrides and oxides in metastable crystallographic structures. The calculations involved are based on the classical alloying criteria of atomic size, valence and electronegativity, and incorporate a correction factor obtained... 

It was evident to early workers in the field that such F-sugars should be capable of existence if only on the grounds of the similarity of the F-atom to the OH group in size, electronegativity and ability to peurticipate in H-bonded structures. Interest was further fuelled by the discovery of the high toxicity of monofluoro-acetate and by the bizcurre fact that this compound occurred in Nature in many plants. 

In the construction of aquaphilic migration forms can participate practically all elements of the Mendeleyev Table except for noble gases. Their properties depend first of all on the properties of elements of their composition. Major in this case are such properties of elements as their size, electronegativity and ionization energy of individual atoms, which define charge, size and ionic potential of migration forms. 

Another property that is closely related to electronegativity and position in the periodic table is polarizability. Polarizability is related to the size of atoms and ions and the... 

The mles can readily be extended to isoelectronic anions and carbaboranes (BH=B =C) and also to metalloboranes (p. 174), metallocarbaboranes (p. 194) and even to metal clusters themselves, though they become less reliable the further one moves away from boron in atomic size, ionization energy, electronegativity, etc. 

Fluorine has a number of peculiarities that stem from its high electronegativity, small size, and lack of available d-orbitals. It is the most electronegative element of all and has an oxidation number of — 1 in all its compounds. Its high electronegativity and small size allow it to oxidize other elements to their highest oxidation numbers. The small size helps in this, because it allows several F atoms to pack around a central atom, as in IF7. 

When the electronegativity and the size of the ligand atoms have opposing influence, no safe predictions can be made ... 

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