Molecule attraction

This tliird part can be substituted by a functional group, a small fragment or even a polymer, where alkanetliiols are only used to attach tire whole compound to tire surface. This potential makes compounds modified witli SA molecules attractive in a whole variety of areas and teclmologies. 

The sodium end of the molecule attracts water. The long hydrocarbon chain at the other end attracts oils and fats. 

Polar molecules attract other polar molecules through dipole-dipole intermolecular forces. Polar solutes tend to have higher solubilities in polar solvents than in nonpolar solvents. Which of the following pairs of compounds would be expected to have the higher solubility in hexafluorobenzene, Cf,I... 

Molecules am act one another. Fiuni that simple fact spring fundamentally important consequences. Rivers, lakes, and oceans exist because water molecules attract one another and form a liquid. Without that liquid, there would be no life. Without forces between molecules, our flesh would drip off our bones and the oceans would be gas. Less dramatically, the forces between molecules govern the physical properties of bulk matter and help to account for the differences in the substances around us. They explain why carbon dioxide is a gas that we exhale, why wood is a solid that we can stand on, and why ice floats on water. At very close range, molecules also repel one another. When pressed together, molecules resist further compression. 

FIGURE 5.3 Polar molecules attract each other by the interaction between the partial charges of their electric dipoles (represented by the arrows). Both the relative orientations shown (end to end or side by side) result in a lower energy. 

Many fluids show a decrease in viscosity with increasing shear rate. This behavior is referred to as shear thinning, which means that the resistance of the material to flow decreases and the energy required to sustain flow at high shear rates is reduced. These materials are called pseudoplastic (Fig. 3a and b, curves B). At rest the material forms a network structure, which may be an agglomerate of many molecules attracted to each other or an entangled network of polymer chains. Under shear this structure is broken down, resulting in a shear... 

Here we present and discuss an example calculation to make some of the concepts discussed above more definite. We treat a model for methane (CH4) solute at infinite dilution in liquid under conventional conditions. This model would be of interest to conceptual issues of hydrophobic effects, and general hydration effects in molecular biosciences [1,9], but the specific calculation here serves only as an illustration of these methods. An important element of this method is that nothing depends restric-tively on the representation of the mechanical potential energy function. In contrast, the problem of methane dissolved in liquid water would typically be treated from the perspective of the van der Waals model of liquids, adopting a reference system characterized by the pairwise-additive repulsive forces between the methane and water molecules, and then correcting for methane-water molecule attractive interactions. In the present circumstance this should be satisfactory in fact. Nevertheless, the question frequently arises whether the attractive interactions substantially affect the statistical problems [60-62], and the present methods avoid such a limitation. 

The earliest model was provided by Helmholtz, and is shown schematically in Figure 2.2(a) for a negatively charged electrode. Immediately next to the electrode is a layer of water molecules, attracted via their dipoles. As a result of coulombic attraction, cations approach the electrode as close as their... 

Permanent-dipole/permanent-dipole forces are weak attractive forces between permanently polar molecules. S+ atoms in one molecule attract S atoms in another molecule. They act in addition to the induced-dipole/induced-dipole forces. 

The charges formed are not full charges as found in ions. These are only partial charges, indicated by a delta, S. Many times these polar bonds are responsible for the entire molecule being polar. The molecule is polar if it has a negative end and a positive end. Polar molecules attract other polar molecules, and this attraction may greatly influence the properties of that substance. (We will see the consequences of this in Chapter 11.)... 

C—Real gases are different from ideal gases because of two basic factors (see the van der Waals equation) molecules have a volume, and molecules attract each other. The molecules volume is subtracted from the observed volume for a real gas (giving a smaller volume), and the pressure has a term added to compensate for the attraction of the molecules (correcting for a smaller pressure). Since these are the only two directly related factors, answers B, D, and E are eliminated. The question is asking about volume thus, the answer is C. You should be careful of NOT questions such as this one. 

The polarity of a molecule determines its solubility. Polar molecules attract each other, so polar molecules usually dissolve in polar solvents, such as water. Non-polar molecules do not attract polar molecules enough to compete against the strong attraction between polar molecules. Therefore, nonpolar molecules are not usually soluble in water. Instead, they dissolve in non-polar solvents, such as benzene. 

In this section, you have pieced together the main components that determine the structure and polarity of molecules. Why is the polarity of a molecule important Polar molecules attract one another more than nonpolar molecules do. Because of this attraction, many physical properties of substances are affected hy the polarity of their molecules. In the next section, you will consider some of these physical properties for liquid and solid substances, and learn about other forces that have a significant effect on the interactions within and among molecules. 

The Friedel-Crafts reaction is one of the most important and versatile tools for the formation of carbon-carbon bonds in the synthesis of substituted aromatic and heteroaromatic compounds present in numerous natural products and drugs. Catalytic asymmetric variants using either metal complexes or organic molecules attracted considerable attention over the last few years. 

A molecule of a liquid attracts the molecules that surround it, and, in its turn, it is attracted by them (Figure 1.2). For the molecules that are inside a liquid, the resultant of all these forces is neutral, and all of them are in equilibrium by reacting with each other. When these molecules are on the surface, they are attracted by the molecules below and by the lateral ones, but not toward the outside. The resultant is a force directed inside the liquid. In its turn, the cohesion among the molecules supplies a force tangential to the surface. So, a fluid surface behaves like an elastic membrane that wraps and compresses the liquid below. The surface tension expresses the force with which the surface molecules attract each other. It is common observation that, due to the surface tension, it takes some effort for some bugs to climb out of the water in lakes. On the contrary, other insects, such as the marsh treaders and water striders, exploit the surface tension to skate on the water without sinking (Figure 1.3). 

Another characteristic dependent on the intermolecular forces is the surface tension of the liquid. Surface tension results from the unbalanced forces on molecules at the surface of a liquid. Figure 8.11 shows how surface tension results from these unbalanced forces. Consider water as the liquid in Figure 8.11. A water molecule in the interior of the liquid is surrounded on all sides by other water molecules. Attractive intermolecular forces pull the molecule equally in all directions and these forces balance out. A water molecule on the surface experiences an unbalanced force toward the interior of the fluid. This unbalanced force pulls on the surface of the water putting it under tension. This situation is similar to the tightening of the head of drum. The tension causes the surface of the water to act like a thin film. If you carefully use tweezers to place a clean needle on the surface of water, surface tension will allow the needle to float even though the needle is denser than water. 

The cleaning power of soaps can be attributed to the polar characteristics of the soap molecule. Long chain hydrocarbons are represented by the R s in Figure 15.16. This end of the molecule is nonpolar and tends to dissolve in nonpolar oils and grease (remember the rule from Chapter 11 that like dissolves like ). The other end of the soap molecule is ionic and dissolves in water. The process of how soap works can be thought of as one end of the soap molecule attracting the grease and oil particles and the other end... 

It is known that two molecules attract each other when they are far apart and repel each other when they come close together. 

At 25°C, both compounds are in liquid phase. In pure liquids whose pcirticles have less intermolecular (between-molecule) attraction, the vapor pressure is higher because the molecules at the surface of the liquid can more easily escape into vapor (gas) phase. 

Asymmetric oxidation of prochiral sulfides is one of the most effective routes for the preparation of chiral sulfoxides. These latter molecules attract great interest, as they are useful synthons for some drugs. They can also be used as chiral auxiliaries due to their configurational stability. The oxidation can be performed by using complexes... 

Real gases, on the other hand, consist of atoms or molecules that interact through intermolecular forces. Atoms/molecules attract at distant range and repel at near range they may be thought of as having a finite size. The theory of real gases accounts for these facts by means of a virial expansion,... 

Water molecules attract one another because each contains a slightly positive side and a slightly negative side. The molecules position themselves such that the positive side of one faces the negative side of a neighbor. 

POLAR MOLECULES ATTRACT OTHER POLAR MOLECULES... 

By what means are ethanol and water molecules attracted to each other ... 

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