Nonbonding intermolecular interactions

There are three types of nonbonding intermolecular interaction dipole-dipole interactions, van der Waals forces and hydrogen bonding. These interactions increase significantly as the molecular weights increase, and also increase with increasing polarity of the molecules. 

Physical Properties of Alkanes and Nonbonding Intermolecular Interactions A CLOSER LOOK AT... Hydrogen Bonding... 

Physical Properties of Alkanes and Nonbonding Intermolecular Interactions... 

Hydrogen bonding and van der Waals attractions are examples of nonbonding intermolecular interactions. These kinds of interactions have important consequences for the properties and behavior of molecules, and we will encounter more examples as we continue to explore the chemistry of different classes of organic compounds. 

Hydrc en bonding and van der Waals attractions are nonbonding intermolecular interactions. 

This discrqumt between the experimait and the above calculations may be naturally explained by the fact that the latta do not take into account the steric potential, Le. the term Q ra in the expression (13) for Q( ). This term is a result of indispensable involvement (because correlation in the motion) of the groups adjacent to the rotation axis into the event of torsional motion, especially for rotation at large angles when the torsicmal vibrations the neighbouring monomeric units caimot be considered as independent ones. Thus, the real potential barrier for torsional vibrations in the maoomolecules is rather controlled by nonbonded (intermolecular) interactions betv n the nearest units of the chain involvol in the motion rather than by the value of Qq, Le. = Qq + where the sum extends over all units of the correlation drain part. 

Functions and partly also constants for nonbonded interactions within single molecules (intramolecular interactions) have been taken over in many cases from investigations of interactions between different molecules (intermolecular interactions) (7,3). The derivation of parameters for nonbonded interactions presents further difficulties, e.g. the problem of the anisotropy of such interactions (8, 23) and parameter correlations (Section 2.4.). There is no agreement on the question whether pairs of atoms separated by a chain of only three bonds should be counted as nonbonded interactions. Some authors include these pairs,... 

However, so far all the applications of the JT effect theory were realized only for chemically bonded systems in their high-symmetry configuration and transition states of chemical reactions. We show here that this is an unnecessary restriction the JT type instability is inherent to all the cases of degeneracy or pseudodegeneracy in molecular systems and condensed matter including nonbonded states in molecule formation from atoms, intermolecular interaction, and chemical reactions. 

The network of chemical bonds within molecules only partially determines the chemical and physical properties. Intermolecular interactions cause gases to deviate from the ideal gas law (as we will discuss in Chapter 7) or condense into liquids. Interactions between nonbonded atoms in the same molecule cause proteins to fold into specific configurations, which catalyze chemical reactions critical to life. 

The considerations on the intermolecular interactions can be conveniently reduced to considerations of atom-atom nonbonded interactions. Although these interactions can be treated by nonempir-ical quantum mechanical calculations, empirical and semi-empirical approaches have also proved useful in dealing with them. In the description of the atom-atom nonbonded interactions it is supposed that the van der Waals forces originate from a variety of sources. 

---