Network covalent bond

Quartz (Si02) has a network covalent bond structure... 

Define network covalent bonds list four substances that have a network covalent structure. 

Covalent network Covalent bonds Hard, high-melting C (diamond, graphite), Si02... 

Silicon carbide, SiC covalent-network covalent bonds 2,700°C (sublimes)... 

Figure 3 A portion of the network covalent bonding in Si02-...

Tellurium, like antimony, is slightly more metallic than the preceding group member but stiU displays network covalent bonding. 

H-bonds and dispersion forces. Ceramics ionic and network covalent bonds. 25.43 Fluoroapatite is less soluble than hydroxyapatite, particularly in acidic solutions. Dental flUings must also be insoluble. 25.45 The molecule is long, flat and rigid, so it should form a liquid crystal. 

Boron is similar to carbon in that it has a capacity to form stable covalently bonded molecular networks. Carbonates, metalloboranes, phosphacarboranes, and other families comprise thousands of compounds. 

If the concentration of junction points is high enough, even branches will contain branches. Eventually a point is reached at which the amount of branching is so extensive that the polymer molecule becomes a giant three-dimensional network. When this condition is achieved, the molecule is said to be cross-linked. In this case, an entire macroscopic object may be considered to consist of essentially one molecule. The forces which give cohesiveness to such a body are covalent bonds, not intermolecular forces. Accordingly, the mechanical behavior of cross-linked bodies is much different from those without cross-linking. 

Molecularly imprinted polymers (MIPs) can be prepared according to a number of approaches that are different in the way the template is linked to the functional monomer and subsequently to the polymeric binding sites (Fig. 6-1). Thus, the template can be linked and subsequently recognized by virtually any combination of cleavable covalent bonds, metal ion co-ordination or noncovalent bonds. The first example of molecular imprinting of organic network polymers introduced by Wulff was based on a covalent attachment strategy i.e. covalent monomer-template, covalent polymer-template [12]. 

Restraining the swelling of the fiber by creating acrosslinked network, due to covalent bonding, between matrix and fiber. 

Several nonmetallic elements and metalloids have a network covalent structure. The most important of these is carbon, which has two different crystalline forms of the network covalent type. Both graphite and diamond have high melting points, above 3500°C. However, the bonding patterns in the two solids are quite different... 

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