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Repulsive force, between electrons

In practice, the harmonic oscillator has limits. In the ideal case, the two atoms can approach and recede with no change in the attractive force and without any repulsive force between electron clouds. In reality, the two atoms will dissociate when far enough apart, and will be repulsed by van der Waal s forces as they come closer. The net effect is the varying attraction between the two in the bond. When using a quantum model, the energy levels would be evenly spaced, making the overtones forbidden. [Pg.167]

The difference in repulsive forces between electron pairs means that when lone pairs are present the geometries change. Let s examine two common substances to see how the presence of lone pairs affects the geometries of molecules. Ammonia, NH3, contains three bonding pairs and one lone pair surrounding the nitrogen atom ... [Pg.81]

The electrons in the n" orbital do not appreciably affect the stability of the species. Therefoie all three sptecies are more stable than the corresponding alkyl systems C3H7, CjH,-, and C,H7 . The extra electrons do increase the repulsive forces between electrons slightly, so the order of stability is C H, >... [Pg.151]

Solids aren t really solid They are mostly empty space When we discuss the structure of an atom in Chapter 3 you will learn that the size of the nucleus is actually very tiny compared to the size of the atom. The space that an atom effectively occupies really has to do with the fact that the electrons are moving very quickly and that the repulsive forces between electrons of different atoms keep them a certain distance apart. If you could strip the electrons off an atom and neutralize the charge of the nucleus, the atom would occupy only a fraction of its original size. To picture the size change, if the original size of the atom was about the size of a baseball stadium, the altered atom would be about the size of a marble. Just think The solid floor that you stand on is almost completely empty space ... [Pg.21]

In Chapter 7, we discussed the shielding effect that electrons close to the nucleus have on outer-shell electrons in many-electron atoms. The presence of shielding electrons reduces the electrostatic attraction between the positively charged protons in the nucleus and the outer electrons. Moreover, the repulsive forces between electrons in a many-electron atom further offset the attractive force exerted by the nucleus. The concept of effective nuclear charge allows us to account for the effects of shielding on periodic properties. [Pg.295]

In forming an anion, an atom gains additional electrons in its outermost (valence) shell. Having additional electrons in the valence shell increases the repulsive forces between electrons, and the outermost shell becomes larger to accommodate this repulsion. [Pg.817]

The magnitude of the repulsion force between electron pairs depend on the proximity of each pair to the central atom. Lone pairs lie closer to the central atom than bond pairs, since lone pairs have no other nearby positive nucleus to attract them away from the centre. Bond pairs are attracted by a second nucleus and so they are drawn... [Pg.71]

VSEPR) modeL A model that accounts for the geometrical arrangements of shared and unshared electron pairs around a central atom in terms of the repulsive forces between electron pairs. (10.1) van der Waals equation. An equation that describes the relationships among P, V, n, and T for a nonideal gas. (5.7) van der Waals forces. The collective name for certain attractive forces between atoms and molecules, namely, dipole-dipole, dipole-induced dipole, and dispersion forces. (12.2)... [Pg.779]

Nonbonded interactions are the forces be tween atoms that aren t bonded to one another they may be either attractive or repulsive It often happens that the shape of a molecule may cause two atoms to be close in space even though they are sep arated from each other by many bonds Induced dipole/induced dipole interactions make van der Waals forces in alkanes weakly attractive at most distances but when two atoms are closer to each other than the sum of their van der Waals radii nuclear-nuclear and electron-electron repulsive forces between them dominate the fvan derwaais term The resulting destabilization is called van der Waals strain... [Pg.111]

The temperature-independent van der Waals parameters a and b are unique for each gas and are determined experimentally (Table 4.5). Parameter a represents the role of attractions so it is relatively large for molecules that attract each other strongly and for large molecules with many electrons. Parameter b represents the role of repulsions it can be thought of as representing the volume of an individual molecule (more precisely, the volume per mole of molecules), because it is the repulsive forces between molecules that prevent one molecule from occupying the space already occupied by another molecule. [Pg.290]

It is impossible to carry out this program of directly evaluating the energy integral except in the simplest cases but rough energy curves for various electronic structures can often be constructed by semi-empirical methods, and the discussion outlined above carried out with them. Thus information regarding the repulsive forces between ions obtained from the observed properties of ionic crystals can be used for ionic states of mole-... [Pg.308]

It should be noted that the above conclusions have been reached on strictly electrostatic grounds a spin property has not been invoked for the two electrons. From the variation of i/i along the box it can be shown that the singlet state is of higher energy than the triplet because the two electrons are more crowded together for (S-state) than for (T-state). Thus there is less interelectronic repulsion m the T-state. The quantity 2J j. is a measure of the effect of electron correlation which reduces the repulsive force between the two electron (Fermi correlation energy). [Pg.63]

Region II each nucleus increasingly attracts the other s electron => the attraction more than compensates for the repulsive force between the two nuclei (or the two electrons) => the attraction lowers the energy of the total system... [Pg.29]

The crystal field effect is due primarily to repulsive effects between electron clouds. As we have already seen, the repulsive energy is of opposite sign with respect to coulombic attraction and the dispersive forces that maintain crystal cohesion. An increase in repulsive energy may thus be interpreted as actual destabilization of the compound. [Pg.67]

In each of our examples, only bonding pairs of electrons surrounded the central atom. Many times the central atom contains a single lone pair or lone pairs of electrons in addition to bonding pairs. The presence of lone pairs, which occupy more space than bonding pairs, affects the repulsive forces between the valence electrons in molecules. [Pg.81]


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See also in sourсe #XX -- [ Pg.27 , Pg.28 ]




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