Carbon atoms, bonding nature

A wide variety of carbon materials, natural as well as synthetic, exist. Carbon is a polymer consisting of a hexagonal network of carbon atoms bonded to each other by sp2 hybrid orbitals the tr-bonds are parallel to the carbon network with a rc-bond perpendicular to it. The network structure of carbon is illustrated in Figure l.14... 

Where (RJ is joined to the double bond through a carbon atom, the nature of R determines which orbital will be used to pair up with the sp2 orbital. In all the compounds shown below a saturated carbon atom with four bonds is joined to the double bond. The C-C single bond is a G bond between... 

Although the cyanohydrin is an uncommon functional group, linamarin and amygdalin are two naturally occurring cyanohydrin derivatives. Both contain a carbon atom bonded to both an oxygen atom and a cyano group, analogous to a cyanohydrin. 

As you know, carbon forms four bonds. Hydrogen, having only one valence electron, forms only one covalent bond by sharing this electron with another atom. Therefore, the simplest hydrocarbon molecule consists of a carbon atom bonded to four hydrogen atoms, CH4. This substance is called methane and is an excellent fuel and the main component of natural gas. 

A carbon atom can form four covalent bonds. In the simplest hydrocarbon, methane, a single carbon is bonded to four hydrogen atoms. Methane is the main component of the natural gas that you burn when you light a Bunsen burner. The next simplest hydrocarbon, ethane, is formed when two carbon atoms bond to each other as well as to three hydrogen atoms apiece. 

Sulphonic acids (1) are strong acids, usually comparable with sulphuric acid, that contain a carbon atom bonded to a sulphur(VI) moiety. They are found only rarely in nature. 

Fatty acids are carboxylic acids with long hydrocarbon chains. The fatty acids most frequently found in nature are shown in Table 26.1. Because they are synthesized from acetate, a compound with two carbon atoms, most naturally occurring fatty acids contain an even number of carbon atoms and are unbranched. The mechanism for the biosynthesis of fatty acids is discussed in Section 19.21. Fatty acids can be saturated with hydrogen (and therefore have no carbon-carbon double bonds) or unsaturated (have carbon-carbon double bonds). Fatty acids with more than one double bond are called polyunsaturated fatty acids. Double bonds in naturally occurring unsaturated fatty acids are never conjugated—they are always separated by one methylene group. 

With the exception of glycine, the amino acids have chiral central carbon atoms. The naturally occurring amino acids are of the L isomer form. These 20 amino acids are linked into a polymeric structure via peptide bonds formed by the condensation of the carboxyl and amino groups of adjacent amino acids ... 

In organisms ranging from bacteria to humans, there are 20 common amino acids that share structural and stereochemical motifs. In each amino acid there is a central carbon atom bonded to a hydrogen atom, an amine, and a carboxylic acid. At neutral pH, the amines and carbo>qrlic acids exist as ammonium ions and carboxylates, respectively. In addition, for 19 of the 20 amino acids, there is a fourth group on the central carbon other than hydrogen, referred to as a"side chain". The central carbon of these 19 amino acids is therefore a chiral center, and all 19 natural... 

The simplest hydrocarbon is methane or natural gas. Methane has one carbon atom and four hydrogen atoms. Close examination of the atomic structure of methane indicates that the outer valence electrons tend to couple in pairs. Compounds made up of carbon atoms have four possible bonds on each atom. The four arms (valence electrons) on each carbon atom bond with a hydrogen or another carbon atom. Each slot on the carbon atom must be filled. There are millions of possible combinations for these carbon atoms. Chemists have divided these hydrocarbons into two very large families alkanes and olefins. 

With regards to the overall balance of combustion, the chemical structure of the motor or heating fuel, e.g., the number of carbon atoms in tbe chain and the nature of the bonding, does not play a direct role the only important item is the overall composition, that is, the contents of carbon, hydrogen, and — eventually— oxygen in the case of alcohols or ethers added to the fuel. 

Pure carbon occurs naturally in two modifications, diamond and graphite. In both these forms the carbon atoms are linked by covalent bonds to give giant molecules (Figure S.2). 

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