Repulsive intermolecular forces

There are two types of intermolecular forces repulsive forces and attractive forces. These are represented by plots of potential energy versus intermolecular separation in Fig. 4, where the forces are given by the negative of the slopes of the... 

Electrostatic (coulombic) interactions among molecules give rise to intermolecular forces, repulsive and attractive. The former are dominant at short intermolecular distances, the latter at larger ones (Figure 7.2). 

The equation of state should reflect the intermolecular forces, repulsive and attractive, that play a major role in determining the volumetric behavior of a fluid. Thus, a typical cubic equation of state is of the form ... 

Intermolecular forces (Section 2.17) Forces, either attractive or repulsive, between two atoms or groups in separate molecules. 

Force The product of mass times acceleration. See also Attractive forces Repulsive forces dipole, 237-238 dispersion, 236,104,107 intermolecular, 227-228,235-236 Formal charge The charge that an atom would have if the bonding electrons in a molecule were equally shared, 171-172,192-193q... 

The presence of intermolecular forces also accounts for the variation in the compression factor. Thus, for gases under conditions of pressure and temperature such that Z > 1, the repulsions are more important than the attractions. Their molar volumes are greater than expected for an ideal gas because repulsions tend to drive the molecules apart. For example, a hydrogen molecule has so few electrons that the its molecules are only very weakly attracted to one another. For gases under conditions of pressure and temperature such that Z < 1, the attractions are more important than the repulsions, and the molar volume is smaller than for an ideal gas because attractions tend to draw molecules together. To improve our model of a gas, we need to add to it that the molecules of a real gas exert attractive and repulsive forces on one another. 

Real gases consist of atoms or molecules with intermolecular attractions and repulsions. Attractions have a longer range than repulsions. The compression factor is a measure of the strength and type of intermolecular forces. When Z > 1, intermolecular repulsions are dominant when Z < 2, attractions are dominant. 

The parameter a is an indication of the strength of attractive intermolecular forces, and the parameter b is an indication of the strength of repulsive intermolecular forces. See also van der Waals equation. 

Intermolecular forces are attractive or repulsive forces between atoms, molecules, and/or ions. The attractive forces compete with the randomizing factor of kinetic energy. The structure that a particular substance exhibits depends on the... 

We now have three substances remaining methane, CH4, methyl fluoride, CH3F, and krypton difluoride, KrF2. We also have two types of intermolecular force remaining dipole-dipole forces and London forces. In order to match these substances and forces we must know which of the substances are polar and which are nonpolar. Polar substances utilize dipole-dipole forces, while nonpolar substances utilize London forces. To determine the polarity of each substance, we must draw a Lewis structure for the substance (Chapter 9) and use valence-shell electron pair repulsion (VSEPR) (Chapter 10). The Lewis structures for these substances are ... 

Intermolecular forces are the attractive or repulsive forces between atoms, molecules, or ions due to full or partial charges. 

Organic compounds that have the same functional group often have similar physical properties, such as boiling points, melting points, and solubilities. Physical properties are largely determined by intermolecular forces, the forces of attraction and repulsion between particles. Three types of intermolecular forces are introduced below. You will examine these forces further in Chapter 4. 

Forces that influence the physical properties of substances are called intermolecular forces. These are forces of attraction and repulsion that act between molecules or ions. 

We have described the different types of primary bonds, but how do these bonds form in the first place What is it that causes a sodium ion and a chloride ion to form a compound, and what is it that prevents the nuclei from fusing together to form one element These questions all lead us to the topics of intermolecular forces and bond formation. We know that atoms approach each other only to a certain distance, and then, if they form a compound, they will maintain some equilibrium separation distance known as the bond length. Hence, we expect that there is some attractive energy that brings them together, as well as some repulsive energy that keeps the atoms a certain distance apart. 

Commercial PAN is normally produced as an atactic polymer with strong hydrogen-bonded intermolecular forces. Because of repulsion between cyano pendant groups and intermolecular hydrogen bonds, the molecule assumes a crystallizable rodlike conformation. The hydrogen bonds between the rodlike chains create bundles of these chains. PAN may be spun into strong fibers. It has a Tg of 104 C... 

In the previous chapters, the diffusion equation has been used extensively to model fast chemical reaction in solution. By addition of various correction factors (such as intermolecular forces, long-range transfer, solvent structure, hydrodynamic repulsion, etc.), the agreement between experiment and theory can be improved as the model becomes more realistic. Nevertheless, the reactants have been presumed to execute Brownian motion. This is only the long-time limit of their actual behaviour. 

As a simple approximation to reality, the macroscopic density, N, and the reaction strength, Q, and hence qx 1 also, may be presumed to be constant throughout the volume, V. If there are no intermolecular forces, except for a hard core repulsion between sink (so that they cannot overlap), the densities become constant and... 

Intermolecular forces are repulsive at close range (R < Kmm) and attractive at distant range (R > Rmj Rm n is the position of the minimum of the pair interaction potential). At high enough densities most of the common gases form dimers, also called double molecules or (binary) van der Waals molecules. Higher than binary complexes are expected, too, especially at high densities and temperatures comparable to, or lower than the well... 

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