Bonds, chemical disruption energy

Thus we can expect a stable molecular species, LiF. The term stable again means that energy is required to disrupt the molecule. The chemical bond lowers the energy because the bonding electron pair feels simultaneously both the lithium nucleus and the fluorine nucleus. That is not to say, however, that the electrons are shared equally. After all, the lithium and fluorine atoms attract the electrons differently. This is shown by the ionization energies of these two atoms ... 

Norrish has suggested that the low quantum yield is probably due to the complexity of the molecule. Decomposition cannot occur if there is a wide distribution of energy among the various parts of a complex molecule for then there is not a sufficient quantity left at the one particular bond where chemical disruption must occur. The probability that a fraction of the whole amount sufficient for chemical decomposition will reach the proper bond at the proper instant depends largely on the complexity of the molecule and the amount of energy introduced. With acetone this probability appears to be about 0.2 with crotonic aldehyde the probability is zero, for Blacet and Roof35 have shown that this substance does... 

The thermo-chemical study of Sc, Y, La, Pr, Tm and Yb tricyclopentadienides has given close magnitudes of the average metal-ring disruption energy [158]. The tendency of diminishing of the Cp-Ln bond strength from early to heavy REM was found in this case (from 78 kcal/mol for Y to 51 kcal/mol for Yb). 

Various physical factors can cause denaturation (mostly changes in temperature, pressure, exposure to ultrasound and penetrating electromagnetic radiation). Denaturation as a result of chemical agents occurs, for example, in the presence of salts, acids and bases or in the presence of surfactants. For example, heat can be effectively used to disrupt hydrogen bonds and non-polar hydrophobic interactions. This occurs because heat increases the kinetic energy and causes the molecules to vibrate so rapidly and violently that the bonds are disrupted. The activation energy of denaturation by... 

It is to be expected that there will be a gradation in the manner in which the smaller molecules are associated with the network. This may involve both physical and chemical forces such as covalent bonds, dispersion forces and hydrogen bonding, and could involve physical entrapment. It is doubtful whether any single technique can distinguish between these different modes of attachment sufficiently clearly to establish a precise boundary. Different energies will be required to disrupt the different types of attachment. It may be significant... 

Bond Energy. A measure of energy reqd to disrupt a chemical bond. The definitions as used in phvs chem axe discussed in Refs 1 2 Refs 1)H.A.Skinner H.D.Springall,Nature 162, 343-44(1948) 2)L.H.Long, Nature 162,344-45(1948)... 

Thus, the electronic excitation energy is first spent on a chemical bond breaking (the relaxation of the electronically excited site) and, then, a certain part of the energy is released in the form of the heat during the reconstruction of the disrupted bond. The model proposed may explain the high photo stability of the E -centers in Si02. 

Below, it is presented the reaction heat calculated for two DOSG reactions that can elucidate the character of the 0-0 bonding in this group. In the triplet state, the distance between the oxygen atoms in the F2Si(0 )(0 ) molecule increases to 2.5 A i.e., the chemical bond between these atoms is disrupted. The G2(MP2) energy of the triplet state proved to be... 

There is considerable support for the hypothesis that a molecule decomposes unimolecularly when a sufficient amount of energy becomes localized in a particular bond or mode of vibration.19 Knowing these various types of vibration as in the ethyl bromide molecule one is tempted to speculate as to which are the most likely ones to be involved in the chemical reaction. For example, if ethyl bromide decomposes to give a free ethyl radical and a bromine atom as the first step the action must occur by increasing the amplitude of vibration of the fundamental frequency Fi to the point of rupture. On the other hand if the molecule disrupts into ethylene and hydrobromic acid in a single internal operation the fundamental frequency Fq or F8 must be involved. These latter... 

Attractive forces operate between all atoms, but unless the potential energy minimum is at least of the order of RT, the two atoms will not be able to withstand the disruptive influence of thermal energy long enough to result in an identifiable molecule. Thus we can say that a chemical bond exists between the two atoms in H2. The weak attraction between argon atoms does not allow Ar2 to exist as a molecule, but it does correspond to the van Der Waals force that holds argon atoms together in the liquid and solid. 

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