By non-metallic elements

Covalent Bonding Covalent bonds have directional character. Such bonds are generally formed by non-metallic elements. In such compounds the structures can be rationalised by coordination number and bonding geometry of atoms present, e.g.,... 

Rings are generally formed by non-metallic elements with directional covalent bonding, e.g. S8, C6H6,... 

The solutions in these alkali metals are also influenced by non-metallic elements present as contaminants. Oxygen causes the formation of complex oxides as well as in sodium. These compounds are in chemical equilibrium with the dissolved species of the transition elements. 

These elements are generally unaffected by non-oxidising acids (behaviour expected for non-metallic elements) but they do react when heated with concentrated sulphuric and nitric acids, both powerful oxidising agents. Sulphur is oxidised to sulphur dioxide by hot concentrated sulphuric acid,... 

Fig. 2.29. Formation of surface compounds on Fe-15%Cr alloys by cosegregation of chromium and a non-metallic element [2.160]. (a) nitride, (b) carbide, (c) sulfide.

The second part is a review of the materials deposited by CVD, i.e., metals, non-metallic elements, ceramics and semiconductors, and the reactions used in their deposition. 

This chapter is a review of the CVD of non-metallic elements and covers boron, silicon, and germanium. Silicon and germanium are borderline elements with metalloid characteristics. Both are important semiconductor materials, particularly silicon, which forms the backbone of the largest business in the world the electronic industry. All three materials are deposited by CVD on an industrial scale and a wide variety of CVD reactions are available. 

Situated between the solid and gaseous states as the only non-metallic element liquid at ambient temperature, bromine is sandwiched in the periodic table between the ubiquitous chlorine and the rather rare iodine. In terms of production volumes it is neither a bulk commodity chemical like chlorine, nor a speciality chemical like iodine. And commercially, bromine is beset by uncertainty. Until the 1970s, the major market forbromine was in dibromoethane - a co-additive for leaded petrol. The phase-out of lead in petrol could have spelled the collapse of the bromine industry, but alternative bromine markets developed and the industry both rationalised and flourished. However, although world bromine production continues to increase slowly, fresh environmental concerns have emerged and the industry is once more under threat. Details are given. 19 refs. 

Another general method for converting alcohols to halides involves reactions with halides of certain non-metallic elements. Thionyl chloride, phosphorus trichloride, and phosphorus tribromide are the most common examples of this group of reagents. These reagents are suitable for alcohols that are neither acid-sensitive nor prone to structural rearrangements. The reaction of alcohols with thionyl chloride initially results in the formation of a chlorosulfite ester. There are two mechanisms by which the chlorosulfite... 

The behaviour of chlorine irifluoride differs sharply from that of bromine trifluoride for, when it is added to potassium fluoride, the latter may be recovered quantitatively by evaporation in vacuum at room temperature. The same is true of other metallic fluorides and it appears that the (C1F4) anion is inherently unstable. There is some indication that chlorine trifluoride may form acids with the fluorides of some of the non-metallic elements, though this point has not cis yet been fully investigated. No direct evidence is yet available as to whether other halogen fluorides can give rise to acids and bases, though this is perhaps less probable for compounds such as CIF, BrFj and IF7. 

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