Methane covalent bonding

The two kinds of covalent bond are not identical, one being a simple covalent bond, a sigma (ct) bond, the other being a stronger (but more reactive) bond called a n bond (p. 56). As in the formation of methane both elements attain noble gas configurations. We can consider the formation of ethene as the linking of two tetrahedral carbon atoms to form the molecule C2H4 represented as ... 

Protonated methane (CH ) does not violate the octet rule of carbon. A bonding electron pair (responsible for covalent bonding between C and H atoms) is forced into sharing with the proton, resulting in 2 electron-3 center bonding (2e-3c) (see Chapter 10). Higher alkanes are protonated similarly. 

Representing a two electron covalent bond by a dash (—) the Lewis structures for hydrogen fluoride fluorine methane and carbon tetrafluoride become... 

The most important interatomic bond in polymers, and indeed in organic chemistry, is the covalent bond. This is formed by the sharing of one or more pairs of electrons between two atoms. An example is the bonding of carbon and hydrogen to form methane Figure 5.2). 

Bonds may also be broken symmetrically such that each atom retains one electron of the pair that formed the covalent bond. This odd electron is not paired like all the other electrons of the atom, i.e. it does not have a partner of opposite spin. Atoms possessing odd unpaired electrons are termed free radicals and are indicated by a dot alongside the atomic or molecular structure. The chlorination of methane (see later) to produce methyl chloride (CH3CI) is a typical free-radical reaction ... 

Note that there is no one-carbon alkene corresponding to methane, since hydrogen can never form more than one covalent bond, and there is no other carbon atom in the structural formula. Therefore, the first compound in the alkene series is ethene, while the corresponding two-carbon compound in the alkane series, ethane, is the second compound in the series, with methane the first. 

This thermal initiation generates two free radicals by breaking a covalent bond. The aldehyde radical is long-lived and does not markedly influence the subsequent mechanism. The methane radical is highly reactive and generates most reactions. 

Caibon has eight electrons in its valence shell in both methane and carbon tetrafluoride. By forming covalent bonds to four other atoms, carbon achieves a stable electron configuration analogous to neon. Each covalent bond in methane and carbon tetrafluoride is quite strong—comparable to the bond between hydrogens in Fl2 in bond dissociation energy. 

The atoms in the molecules of these pain relievers are covalently bonded. Electrons are shared between atoms in a series of single and double covalent bonds. The covalent bonds in aspirin, acetaminophen, and ibuprofen are similar to those found in methane and carbon dioxide. 

When a covalent bond breaks to produce radicals, i.e. one electron of the bond pair goes to each atom, homolytic fission has occurred. These highly reactive chlorine radicals attack the methane molecules. 

Ben-Naim (1980) has recently reviewed the work in this field. The results obtained so far are not very satisfying because there does not seem to be a single method that can provide direct information on the properties of the hydrophobic interactions between two simple solutes in water at a realistic interparticle distance. Most studies have been concerned with the volume difference between a dimer 2A and a monomer A, for example, ethane and methane. However, such comparisons are not realistic because there is a covalent bond between the two monomers in the dimer, and also two hydrogen atoms are missing in the dimer. The volume of these two hydrogens seems to account for the resulting volume difference. 

This Lewis structure shows methane, the simplest organic compound. The carbon atom has four valence electrons, and it obtains four more electrons by forming four covalent bonds with the four hydrogen atoms. 

The idea here is just the same, except for inevitable refinements and details, for the formation of aU covalent bonds. So the basic ideas for chemical bonding in methane, ammonia, water, and so on, are the same. 

The halogens resemble hydrogen because they need to form a single covalent bond to achieve electronic stability. Consequently, a halogen atom may replace any hydrogen atom in a hydrocarbon. Figure 6-12 shows how fluorine or bromine atoms proxy for hydrogen in methane. 

Alkanes have only -hybridized carbons. The conformation of alkanes is discussed in Chapter 3 (see Section 3.2.2). Methane (CH4) is a nonpolar molecule, and has four covalent carbon-hydrogen bonds. In methane, aU four C—H bonds have the same length (1.10 A), and all the bond angles (109.5°) are the same. Therefore, all four covalent bonds in methane are identical. Three different ways to represent a methane molecule are shown here. In a perspective formula, bonds in the plane of the paper are drawn as solid hues, bonds sticking out of the plane of the paper towards you are... 

Nitrogen attracts three additional electrons and is thus able to form three covalent bonds, as occurs in ammonia, NH3, shown in Figure 6.16. Likewise, a carbon atom can attract four additional electrons and is thus able to form four covalent bonds, as occurs in methane, CH4. Note that the number of covalent bonds formed by these and other nonmetallic elements parallels the type of negative ions they tend to form (see Figure 6.6). This makes sense, because covalent bond formation and negative ion formation are both applications of the same concept nonmetallic atoms tend to gain electrons until their valence shells are filled. 

In all the hydrocarbons discussed so far, including the methane shown in Figure 12.6, each carbon atom is bonded to four neighboring atoms by four single covalent bonds. Such hydrocarbons are known as saturated hydrocarbons. 

Carbon has four valence electrons. Each electron pairs with an electron from a hydrogen atom in the four covalent bonds of methane. 

In a similar way we can visualize the covalent bonds of water and methane. 

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