Silicon covalent compounds

The elements show increasing metallic character down the group (Table 14.6). Carbon has definite nonmetallic properties it forms covalent compounds with nonmetals and ionic compounds with metals. The oxides of carbon and silicon are acidic. Germanium is a typical metalloid in that it exhibits metallic or nonmetallic properties according to the other element present in the compound. Tin and, even more so, lead have definite metallic properties. However, even though tin is classified as a metal, it is not far from the metalloids in the periodic table, and it does have some amphoteric properties. For example, tin reacts with both hot concentrated hydrochloric acid and hot alkali ... 

A rapid and versatile covalent assembly technique starting from DEE oligomers has provided the 11.9 nm long hexadecameric poly(triacetylene) rod 20.1481 With its linearly conjugated 16 double and 32 triple bonds spanning in-between the terminal silicon atoms, compound 20 is currently the longest linear, fully Jt-conjugated molecular wire without aromatic repeat units in the backbone. 

Like carbon, silicon is able to form covalent compounds. Unlike carbon, silicon is not able to form double or triple bonds. Hence silicon is able to form compound by condensation reaction. 

Polar framework compounds. These are compounds where no individual molecules exist, and range from ionic compounds like sodium chloride, through part-ionic, part-covalent compounds like aluminum oxide, to polar covalent framework solids like silicon dioxide. 

The elements show increasing metallic character down the group (Table 14.12). Carbon has definite nonmetallic properties it forms covalent compounds with nonmetals and ionic compounds with metals. The oxides of carbon and silicon are acidic. Germanium is a typical metalloid... 

Carbon is the definitive nonmetal, considering its vast variety of covalent compounds. The diamond structure (3 2PT, Section 4.4.3) has a network of tetrahedra. The next two elements of the carbon family, silicon and germanium, have the diamond structure, and lead is cubic close-packed. Tin shows an interesting variation. The low temperature form of tin (stable below 13.2°C) is gray tin with the diamond structure. The CN of Sn is 4, the Sn—Sn distance is 2.80 A and a0 = 6.4912. Ordinary tin, the "high temperature form, is white tin. In our time tin is used primarily for tin plate on iron for food containers, tin cans. In earlier periods utensils were often cast tin. In cold climates sometimes a tin utensil would crumble from "tin disease," resulting from conversion of white tin to gray tin. The conversion is slow, but once started, nucleation causes spread of the "disease."... 

In the foregoing discussion there has been no intention of minimizing the importance or the scientific interest of the remaining types of volatile covalent compounds of silicon, such as the silylamines.41 Emphasis has been placed on the hydrides, halides, and esters, only because they are more important to the present methods for preparing the organosilicon products described in later chapters. 

Included among the interesting properties currently being pursued in some Zintl phases are the metal-nonmetal transition and colossal magnetoresistance. Zintl phases have also been used as precursors in the synthesis of novel solid-state materials. For example, afullerene-type silicon clathrate compound, Na2BagSi46 (clathrates are covalent crystals, whereas fullerides are molecular crystals), with a superconducting transition at... 

The ionisation potentials (Table 58) indicate that silicon is capable of forming positive ions more easily than carbon, but it too forms mainly covalent compounds. 

What are the formulas of the covalent compounds involving (a) one carbon atom and as much chlorine as needed, (b) one silicon atom and chlorine, and (c) one sulfur atom and chlorine ... 

Carbon also forms a covalent compound with silicon. Silicon carbide, SiC, is called carborundum and is prepared as follows ... 

The leading element in the group, carbon, which will be our main concern, forms only covalent compounds. The other elements in the group—silicon, germanium, tin and lead—also tend to form covalent compounds, but an... 

Covalent carbides, which have giant-molecular structures, as in silicon carbide (SiC) and boron carbide (B4C3). These are hard high-melting solids. Other covalent compounds of carbon (CO2, CS2, CH4, etc.) have covalent molecules. 

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