Methane line structure

Familiar examples of molecules that contain covalent bonds are hydrogen (H2), water (H20), oxygen (02), ammonia (NH3), and methane (CH4). More information about a molecule is given by its structural formula, in which the individual bonds are shown (indicated by lines). Structural formulas may or may not indicate the actual shape of the molecule. For example, water might be represented as... 

The three-dimensional character of atoms and molecules is difficult to portray without models or computer-generated drawings. Methane and ethane are shown here in Lewis structure and line structure form ... 

FIGURE 14.9 The names, condensed structures, and bond line structures of three simple alkanes (a) methane, (b) ethane, and (c) propane. Practical uses of methane and propane are also given. 

The fundamental V4, measured under high resolution, is shown in Figure 4-35 (located in pocket on inside back cover). The Coriolis interaction interferes with the regular spacing of the fine-line structure of the P-branch, and causes the high-frequency side of the R-branch to become quite irregular. The fundamental V2 for methane has distinct P-, Q-, and R-branches and, under medium resolution, resembles the well-formed band of CO2 at 667 cm ... 

Figure 2-4 Hashed-wedged line structures of methane through pentane. Note the zigzag arrangement of the principal chain and two terminal hydrogens.

Methane is a tetrahedral molecule its four hydrogens occupy the corners of a tetra hedron with carbon at its center We often show three dimensionality m structural for mulas by using a solid wedge ) to depict a bond projecting from the paper toward you and a dashed wedge (i 111 ) for one receding away from you A simple line (—)... 

The axes of the sp orbitals point toward the corners of a tetrahedron Therefore sp hybridization of carbon is consistent with the tetrahedral structure of methane Each C—H bond is a ct bond m which a half filled Is orbital of hydrogen over laps with a half filled sp orbital of carbon along a line drawn between them... 

In the 1930s when high-pressure natural gas (95% methane) pipelines were being built in the United States, it was found that the lines often became plugged in cold weather by a white, waxy solid that contained both water and methane (CFIJ molecules. Twenty years later. Walter Claussen at the University of Illinois deduced Ihe structure of that solid, a hydrate of methane. Notice (Figure B) that CH4 molecules are trapped within a three-dimensional cage of H20 molecules. 

Figure 4. Schematic potential energy surface for the reaction of FeO" " with methane. The sohd line indicates the sextet surface the quartet surface is shown with a dotted line, in each case leading to the production of Fe + CH3OH. The dashed line leads to formation of FeOET + CH3. The pathway leading to the minor FeCH2" + H2O channel is not shown. Schematic structures are shown for the three minima the [OFe CHJ entrance channel complex, [HO—Fe—CH3] insertion intermediate, and Fe" (CH30H) exit channel complex. See text for details on the calculations on which the potential energy surface is based.

Figure 11.12 The three-dimensional tetrahedral structure of carbon (e.g., in methane, CH4), with an angle between the bonds of 109.5°. The simple straight lines are in the plane of the paper, the solid tapered line points towards the observer and the dashed line is into the paper.

A great deal of experience informs us that carbon atoms frequently form molecules in which they are simultaneously linked to four other atoms, hi contrast, hydrogen atoms are usually linked to only one other atom. It follows that the methane molecule is structured with a central carbon atom to which are bonded the four hydrogen atoms. In such a structure, only carbon-hydrogen (C-H) bonds exist. We can represent methane in the following way, in which the solid lines are symbols for chemical bonds ... 

In the light of the more complete study of ring-halogenated triphenylchloro-methanes in this paper, the free radical hypothesis was back - if it ever was excluded in the previous paper - in the final discussion of the constitution of triphenylmethyl , now with two tautomeric triphenylmethyl radical structures in equilibrium with each other and the Jacobson dimer 1 (Scheme 2). Note that the radical was symbolized by an open valence (a thick line is used here for clarity). The strong results obtained with 3 (Scheme 1) were explained by removal of the quinoid bromine atom from 4 giving a radical 6 which tautomerized to the triphenylmethyl analogue 7. By analogy with the... 

The opposed-flow situation has been used very successfully to study the structure of flames as a function of fluid mechanical strain rates. Figure 6.20 illustrates one such flame experiment. Here flow issues from two porous plates in an opposed-flow configuration. The velocity leaving each plate is uniform across the plate surface and the temperature and composition is also uniform. One flow stream is air and the other contains methane, and both streams are seeded with small titania particles. By illuminating the flow with a sheet of laser light, we see streak lines that are formed by the particles as they follow the flow. In the... 

Mehta and Sloan (1996b) present data in Table 4.9 for 19-structure H hydrates formers along uni variant four-phase lines. With only three exceptions, the enthalpy of hydrate formation is 79.5 kJ/mol 7%. In each case, methane occupies the 512 and the 435663 cages while the larger guest occupies the 51268 cage. 

The reaction of ferrocenecarbaldehyde (98) and resorcinol (99) under acidic conditions gave the phenolic macrocycle (100), which on addition of chlorobromomethane in the presence of a base produced the first redox-active cavitand (141,142) (101) (Scheme 31). An X-ray structural investigation on crystals of (101), obtained from a dichlorometh-ane-diethyl ether solvent mixture, revealed the inclusion of a dichloro-methane guest molecule within the cavitand host cavity (Fig. 23). Related redox-active cavitand host molecules ((102) and (103)) containing ferrocene moieties lining the wall of the cavitand cavity have also been prepared by our group (141, 142). 

Figures 20.4.4(a) and 20.4.4(b) illustrate the crystal structure of the 1 1 complex of tetraphenylmethane and carbon tetrabromide. The nodes comprise C(C6H5)4 and CBr4 molecules, and the each linking rod is the weak interaction between a Br atom and a phenyl group. The hexamethylenetetramine-like structural unit is outlined by broken lines. Figures 20.4.4(c) and 20.4.4(d) show the crystal structure of tetrakis(4-bromophenyl)methane, which has a distorted diamondoid network based on the hexamethylenetetramine building unit. If the synthon composed of the aggregation of four Br atoms is considered as a node, then two kinds of nodes (Br4 synthon and quatenary C atom) are connected by rods consisting of p-phenylene moeities.

---