Array three-dimensional

In contrast to the older techniques, a newer method is to use a scanning tuimeling electron microscope to deposit metal coatings in microscopic images as small as 0.001 pm. The ultimate surface metallization techniques allow deposition of metals atom by atom in controlled three-dimensional arrays. 

The crystal stmcture of CrOF has been found to be an infinite three-dimensional array of corner shared CrOF octahedra (57). The species [CrOX ] , ... 

When groundwater contaminant plumes are suspected of having significant depth as well as lateral distribution, a three-dimensional array of monitoring points is needed to identify and characterize such plumes. Thus, groundwater data must be obtained from a number of different locations and from a number of different depths at each location. As a result, either a large number of drillholes are required, each with separate instrumentation installed, or instruments must be combined and installed at multiple levels in each of a smaller number of drillholes. 

At least four series of periodates are known, interconnected in aqueous solutions by a complex series of equilibria involving deprotonation, dehydration and aggregation of the parent acid H5IO6 — cf. telluric acids (p. 782) and antimonic acids (p. 577) in the immediately preceding groups. Nomenclature is summarized in Table 17.24, though not all of the fully protonated acids have been isolated in the free state. The structural relationship between these acids, obtained mainly from X-ray studies on their salts, are shown in Fig. 17.24. H5IO6 itself (mp 128.5° decomp) consists of molecules of (HO)sIO linked into a three-dimensional array by O-H - O bonds (10 for each molecule, 260-278 pm). 

A crystal may be defined as an orderly three-dimensional array of atoms, and all metals are aggregates of more or less imperfect crystals. In considering the structure of metals, therefore, it is convenient to start with the arrangement of atoms in a perfect metal crystal and then to proceed to the imperfections which are always present in the crystal structure. 

The ratio of two chloride ions for each calcium ion results in the formula CaCl2. However, note that this is an empirical formula (Section E). There are no CaCl2 molecules. Crystals of CaCl2 contain many of these ions in three-dimensional arrays. 

The rock-salt structure is a common ionic structure that takes its name from the mineral form of sodium chloride. In it, the Cl- ions lie at the corners and in the centers of the faces of a cube, forming a face-centered cube (Fig. 5.39). This arrangement is like an expanded ccp arrangement the expansion keeps the anions out of contact with one another, thereby reducing their repulsion, and opens up holes that are big enough to accommodate the Na+ ions. These ions fit into the octahedral holes between the Cl ions. There is one octahedral hole for each anion in the close-packed array, and so all the octahedral holes are occupied. If we look carefully at the structure, we can see that each cation is surrounded by six anions and each anion is surrounded by six cations. The pattern repeats over and over, with each ion surrounded by six other ions of the opposite charge (Fig. 5.40). A crystal of sodium chloride is a three-dimensional array of a vast number of these little cubes. 

A similar procedure can be used in predicting interatomic distances in ionic crystals, by evaluating the potential energy of a three-dimensional array of... 

A molecule is a three-dimensional array of atoms. In fact, many of a molecule s properties, such as its odor and chemical reactivity, depend on its three-dimensional shape. Although molecular and structural formulas describe the composition of a molecule, they do not represent the molecule s shape. To provide information about shapes, chemists frequently use ball-and-stick models or space-filling models. 

Individual Na and Cl ions must condense into a three-dimensional array of ions. Energy is released in this condensation, because cations and anions attract each other. We need to examine this attraction in detail to determine how much energy is released in the condensation step. 

The lattice energies of these solids are large enough to make the overall reaction energy-releasing despite the large positive second electron affinity of the anions. In addition, three-dimensional arrays of surrounding cations stabilize the - 2 anions in these solids. 

Quartz left) is a crystalline form of silicon dioxide containing a regular three-dimensional array of Si02... 

Romanov SG, Eokin AV, Tretijakov VV, Butko VY, Alperovich VI, Johnson NP, Sotomayor Torres CM (1996) Optical properties of ordered three-dimensional arrays of structurally confined semiconductors. J Cryst Growth 159 857-860... 

A lattice is a three-dimensional array, and there are eight systems known. Inorganic substances are usually defined by one crystal system by the so-called radius-ratio rule [22], but organic compounds often have the capability of existing in more than one crystal form, a phenomenon referred to as polymorphism. 

Pejova et al. [72] (2008) have obtained three-dimensional arrays of close-packed semiconducting AgBiS2 quantum dots with an average QD radius of 4.2 nm using sonochemical method which was twice as small as compared to the QD solid obtained without ultrasonic irradiation. 

Pejova B, Grozdanov I, Nesheva D, Petrova A (2008) Size-dependent properties of sono-chemically synthesized three-dimensional arrays of close-packed semiconducting AgBiS2 quantum dots. Chem Mater 20(7) 2551-2565... 

The calculation of M for a three-dimensional array is much more complicated, and depends on the structure of the array. For the particular case of the face-centered-cubic NaCl crystal structure, its value is M = 1.747, whereas, for the body-centered-cubic CsCl structure, it is M = 1.763. 

The role of the enzyme s protein scaffold is to hold the zinc ion, coenzyme, and substrate in the three-dimensional array required to lower the energy of the transition state. 

When spherical objects are stacked to produce a three-dimensional array (crystal lattice), the relative sizes of the spheres determine what types of arrangements are possible. It is the interaction of the cations and anions by electrostatic forces that leads to stability of any ionic structure. Therefore, it is essential that each cation be surrounded by several anions and each anion be surrounded by several cations. This local arrangement is largely determined by the relative sizes of the ions. The number of ions of opposite charge surrounding a given ion in a crystal is called the coordination number. This is actually not a very good term because the bonds are not coordinate bonds (see Chapter 16). For a specific cation, there will be a limit to the number of anions that can surround the cation because... 

Chlorine gas is very reactive, and causes horrific bums to the eyes and throat see p. 243. The two atoms are held together by means of a single, non-polar covalent bond. CI2 has a yellow-green colour and, for a gas, is relatively dense at s.t.p. Conversely, table salt (sodium chloride) is an ionic solid comprising Na+ and Cl- ions, held together in a three-dimensional array. What is the reason for their differences in behaviour ... 

Figure 2.13 Diamond has a giant macroscopic structure in which each atom is held in a rigid three-dimensional array. Other covalent solids include silica and other p-block oxides such as A1203...

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