Proton attractive

Various astoichiometric components (hydrogen, carbon, and others, for example, silicium and aluminum) present may interact with localized and nearly free electrons to differing extents. According to the localized free electron interplay model of metal catalysts developed by Knor 163, 164) the ratio of the two types of electrons may influence the catalytic properties considerably. For example, a subsurface proton attracts nearly free electrons and thus uncovers some localized orbitals. Carbon may interact first with localized electrons 164). This may be one of the reasons why their effects are of opposite character. The collective efforts of catalytic and surface chemists are necessary to bring some clarity to the multitude of problems arising here. 

For continuity, the neutral Ne atom is also in the chart, with its atomic radius. As you proceed to the right in Table 5-5, the greater number of protons attracts the electrons more strongly, producing progressively smaller ions. 

The proton attracting power of polar groups can be compared by studying the equilibria in 2 2 -disubstituted diazoaminobenzenes. 

The broad peak observed for tetrabromoguaiacol has its maximum close to 6810 cm 1, showing that the proton attraction of the O—H -Br bond is greater than that of the O—H --0 bond under the steric conditions present in this molecule. 

FIGURE 10.16 The ability of a molecule or ion to act as a strong or weak acid or base depends on its proton-attracting power (represented by the number of triangles) relative to that of the solvent. 

The size of an arsenic atom depends on its valence state and the number of surrounding atoms (its coordination number). When valence electrons are removed from an atom, the radius of the atom not only decreases because of the removal of the electrons, but also from the protons attracting the remaining electrons closer to the nucleus (Nebergall, Schmidt and Holtzclaw, 1976), 141. An increase in the number of surrounding atoms (coordination number) will deform the electron cloud of an ion and change its ionic radius (Faure, 1998), 91. Table 2.2 lists the radii in angstroms (A) for arsenic and its ions with their most common coordination numbers. 

The nitrogen atom, as in aliphatic amines, pyridine etc., exhibits basic properties, that is to say the nitrogen atom can bind a proton through its free electron pair. In pyrrole the resonance possibilities II and III are, however, lost on the addition of a proton, so that the positive ion is thus not stabilized by resonance, whereby the proton attraction, that is the basicity, is very small for pyrrole. The formation of a negative ion, as in pyrrole-potassium, gives no hindrance so that pyrrole does show acid properties. 

The hydrogen bond formation has also an influence on the acidities of, for example, the above-mentioned hydroxybenzoic acids since the proton attraction of the carboxyl group is partially saturated by it and the basicity of the anion is therefore smaller. 

The partial oxidation of methanol to formaldehyde over metal oxides is important industrially, and the results of experiments done in the transient regime are summarized for M0O3 (249). The results in Fig. 41 show that the conversion of methanol and the selectivity toward formaldehyde in a Mars-van Krevelen process are both favored by a relatively oxidized surface. Weber (250) has shown by theoretical calculations that the surface methoxy intermediate should lose one of its hydrogens as a hydride ion attracted to Mo and not as a hydrogen atom or proton attracted to a doublely bonded or bridging oxygen. 

Consider fluorine, which has an electron configuration of ls 2s 2p. Each fluorine atom has seven valence electrons and needs another electron to form an octet. As two fluorine atoms approach each other, several forces act, as shown in Figure 8.2. Two repulsive forces act on the atoms, one from each atoms like-charged electrons and one from each atoms like-charged protons. A force of attraction also acts, as one atoms protons attract the other atoms electrons. As the fluorine atoms move closer, the attraction of the protons in each nucleus for the other atoms electrons increases until a point of maximum net attraction is achieved. At that point, the two atoms bond covalently and a molecule forms. If the two nuclei move closer, the repulsion forces increase and exceed the attractive forces. 

Electrical charges interact in a simple way Like charges repel each other, and unlike charges attract each other. Protons attract electrons, electrons repel electrons, and protons repel protons. 

Ca—O < K—F 19. Anions are larger than the neutral atom, and cations are smaller than the neutral atom. For anions, the added electrons increase the electron-electron repulsions. To counteract this, the size of the electron cloud increases, placing the electrons further apart from one another. For cations, as electrons are removed, there are fewer electron-electron repulsions, and the electron cloud can be pulled closer to tbe nucleus. Isoelectronic same number of electrons. Two variables, the number of protons and the number of electrons, determine the size of an ion. Keeping the number of electrons constant, we have to consider only the number of protons to predict trends in size. The ion with the most protons attracts the same number of electrons most strongly, resulting in a smaller size. 21. a. Cu > Cu > Cu b. Pt > Pd > Ni ... 

Neutrons serve as nuclear cement holding the atomic nucleus u ether. Protons attract btrth other protons and neutrons by the strong nuclear force, but they also repel other protons by the electric force. Neutrons, on the other hand, have no electric charge and so only attract protons and other neutrons by the. strong nuclear force. The presence of neutrons therefore adds to the attraction among nucleons and helps hold the nucleus toother, as illustrated in Figure 4.14. 

Electrons are negatively charged, while the nucleus has a positive charge due to the protons. The protons attract and hold the electrons, but the farther away the electrons are, the less the attractive force. 

Phenol has been interesting many chemists as a model system to study how photo-excited bases in DNA can deactivate to the ground state without resulting in mutation. Not only in such biology-oriented studies, this molecule shows many other interesting features when put in surrounding molecules, clusters, and solvents. Small ammonia clusters are frequently used in place of water-molecule clusters, because ammonia is more proton-attractive than water, and very extensive studies have been performed... 

The relative strength of attraction and repulsion between the charged particles depends on the distance separating the atoms. When the atoms first "sense" each other, the electron-proton attraction is stronger than the electron-electron and proton-proton repulsions. Thus, the atoms are drawn to each other and their potential energy is lowered, as shown in part (b) of Figure 2.2. 

Gordy W, Stanford SC (1941) Spectroscopic evidence for hydrogen bonds comparison of proton-attracting properties of liquids. III. J Chem Phys 9 204-214... 

The chloride anion is isoelectronic with argon. The chloride anion is also slightly larger than the neutral chlorine atom. To complete the octet, the one electron gained went into energy level 3. But now there are 17 protons attracting 18 electrons, so the electrons can move outward a bit. 

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