Covalent-ionic bonding

There are two extreme cases of chemical bonding ionic and covalent. Ionic bonding occurs when there is a complete transfer of one electron from one atom to another to form ionsas in the equation ... 

Transitions between other extreme types of bonds (covalent to metallic covalent to ion-dipole, etc.) can also occur without discontinuity, and the bonds of intermediate character can be discussed in terms of resonance between structures of extreme type in the same way as for covalent-ionic bonds. 

In this chapter, we explored two types of chemical bonds ionic and covalent. Ionic bonds are formed when one or more electrons move from one atom to another. In this way, the atoms become ions—one positive, the other negative—and are held together by the resulting electrical attraction. Covalent bonds form when atoms share electrons. When the sharing is completely equitable, the bond is nonpolar covalent. When one atom pulls more strongly on the electrons because of its greater electronegativity, the bond is polar covalent and a dipole may be formed. 

From the preceding, it might be supposed that covalent character in predominantly ionic compounds always destabilizes the compound. This is not so. Instability results from polarization of the anion causing it to split into a more stable compound (in the above cases the oxides) with the release of gaseous acidic anhydrides. As will be seen in Chapter 16, many very stable, very hard minerals have covalent-ionic bonding. 

There are two main types of bonding, ionic and covalent. Ionic bonding is characterised by the non-directional nature of the Coulombic attractions between ions, i.e. the electrostatic force radiating from the central ion is felt equally in all directions. The main factor that influences the structure of the crystal lattice is the relative sizes of the cations and anions, because this affects how the ions will pack together within the lattice. 

There are two main types of bonding, ionic and covalent. Ionic bonds are characterised by their non-directional nature. The relative sizes of the component ions is the principal factor in determining the structure of the crystal lattice. In contrast, covalent bonds are directional in nature, and of a certain length. Usually in a simple crystal, every ion occupies exactly the same position as does every other ion of the same type. However, in covalent molecules, this is not the case. Thus, every atom in a covalent molecule must be considered individually with respect to its spatial relationship to all the other component atoms. 

Symmetrical covalent Polar covalent Ionic bond bond bonds... 

There is strong primary (covalent/ionic) bonding within each of the layers. However, the bonding between the layers is the weaker van der Waals type. Because the bonding is weak between the sheets, these silicates exhibit perfect one-directional cleavage. 

All semiconductors, elemental or compound, essentially consist of a network of atoms joined by covalent or mixed covalent-ionic bond. These covalent bonds typically involve sp hybrid orbitals that favor tetrahedral coordination, leading to open lattices such as diamond structure (for elemental semiconductors) or its two-component analog, the zinc-blende structure (Figure 14.2a). The covalent bonding is stiff with respect to deformation of the angles between the bonding direction. 

We can broadly classify most chemical bonds into two types ionic and covalent Ionic bonds—which occur between metals and nonmetals—involve the tranrfer of... 

In Summary There are two extreme types of bonding, ionic and covalent. Both derive favorable energetics from Coulomb forces and the attainment of noble-gas electronic structures. Most bonds are better described as something between the two types the polar covalent (or covalent ionic) bonds. Polarity in bonds may give rise to polar molecules. The outcome depends on the shape of the molecule, which is determined in a simple manner by arrangement of its bonds and nonbonding electrons to minimize electron repulsion. 

It is evident from the earlier discussion that scaling among adsorption energies should not be limited to transition metal surfaces. In fact, even for metal-terminated surfaces of more complex systems like transition metal compounds (oxides, nitrides, sulfides, and carbides), where there is mixed covalent, ionic bonding between the... 

Keywords Bond information probes Bond localization Chemical bonds Chemical reactivity Contra-gradience criterion Covalent/ionic bond components Direct/indirect bond multiplicities Entropic bond indices Fisher information Information theory Molecular information channels Orbital... 

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