Chemical formulas bond-line

Much of the communication between insects involves chemical messengers called pheromones A species of cockroach secretes a substance from its mandibular glands that alerts other cockroaches to its presence and causes them to congregate One of the principal components of this aggregation pheromone is the alkane shown in the bond line formula that follows Give the molecular formula of this substance and represent it by a condensed formula... 

Lewis structure (Section 1 3) A chemical formula in which electrons are represented by dots Two dots (or a line) be tween two atoms represent a covalent bond in a Lewis structure Unshared electrons are explicitly shown and sta ble Lewis structures are those in which the octet rule is sat isfied... 

While Lavoisier had established a rational system for naming elements and compounds, Frankland developed the system that we use today for writing chemical formulas and for depicting the bonds between the atoms in molecules. As Frankland synthesized more and more isomers, compounds with the same formulas but different molecular structures, he found traditional formulas confusing they showed the types and numbers of elements but provided no clue as to how the atoms were arranged inside the molecule. To remedy the problem, Frankland depicted the atoms in functional groups and drew lines between them to indicate the bonds between the elements. 

Figure 9.39 Schematic representations of metal 4,4 -bipyridyl porous networks. Lines represent the bipyridyl ligand except for vertical lines in (c), which represent Ag - Ag bonds (2.977 A long), and horizontal lines in (d) which represent Cu---Cu. The chemical formula, framework dimensionality, structure type, degree of interpenetration and pore aperture are listed under each representation. (Reproduced with permission from Reference 38).

A most familiar molecule is water. H20 is the chemical formula for water and a shorthand way to say that each water molecule is made up of two hydrogen atoms and one oxygen atom as shown in Figure 1.3. In the figure, the lines between hydrogen and oxygen represent bonds. 

FIGURE 16.1. Conformational variability of the citrate ion. Shown are (a) the chemical formula, (b) a diagram indicating atom types in (c) which is a line drawing of several superposed citrate structures. The main variability is at the terminal carboxyl groups and rotation about one CH2-C group. Alternate conformers are indicated in (b) by solid bonds for the main conformer and broken lines for another possible conformer. 

Hydrocarbons are classified by whether their carbon structure includes rings, multiple bonds, or branches. Classification of hydrocarbon structural families is shown here with the chemical formula. Structures are shown as Kekule (also called line-bond) and skeletal structures. 

Chemical structures of base pairs. The chemical formula of a double strand of DNA, 2 base pairs long, is shown. The base pairs are picked out in purple. The upper base pair is a G-C pair and the lower one is an A-T pair. The hydrogen bonds are shown as gray, broken lines. The sugar-phosphate backbone is black. 

Fig. 38 a, b. Minor groove binding of netropsin in DNA [100] a chemical formula of netropsin b binding of netropsin by way of N-H- -O bonds dotted lines) and C-H- -C interactions. The latter define the specificity of the drug... 

Write the symbols for the atoms, show which atoms are attached to which, and connect them with a single bond (a line, representing two electrons). Chemical formulas are often written in the order in which the atoms are connected in the molecule or ion. The formula HCN, for example, tells you that the carbon atom is bonded to the H and to the N. In meuiy polyatomic molecules and... 

You should be able to draw chemical formulas that show all of the valence electrons in a molecule (Lewis structures), using lines for bonds and dots to show unshared electrons. You should be proficient in representing structures as dash structural formulas, condensed structural formulas, and bond-line structural formulas. In particular, the more quickly you become skilled at using and interpreting bondline formulas, the faster you will be able to process structural information in organic chemistry. You have also learned about resonance structures, the use of which wiU help us in understanding a variety of concepts in later chapters. 

The dashes at each end of the formulas on lines 1, 2, 3, 4, 7, and 8 are drawn fully inside the enclosing marks, because they do not necessarily denote terminal chemical bonds of the macromolecules. 

A structural formula uses lines to represent chemical bonds and shows how the atoms in a molecule are connected to each other. The structural formula for hydrogen peroxide is H—O—O—H. In addition to formulas, we also use molecular models—fhree-dimensional representations of molecules—to represent compounds. In fhis book, we use two types of molecular models balTand-stick and space-filling. In ball-and-stick models, we represent atoms as balls and chemical bonds as sticks. The balls and sticks are connected to represent the molecule s shape. The balls are color coded, and each element is assigned a color as shown in the margin. 

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