Orbit repelling

We can trace some of the properties of the d-block elements to the shapes of their d-orbitals (see Fig. 1.28). There are two point to keep in mind. First, the lobes of two d-orbitals on the same atom occupy markedly different regions of space. Because they are relatively far apart, electrons in separate d-orbitals repel one another weakly. Second, electron density in d-orbitals is low near the nucleus. Because d-electrons are far from the nucleus, they are not very effective at shielding other electrons from its positive charge. 

Since k is a large negative number, AE is always a destabilizing quantity, which decreases as eav becomes more negative. Therefore, high-lying orbitals repel each... 

Thus, opposite-spin electrons from different atoms will form a bond, but electrons that are already paired up by spin, as happens in a filled orbital, will repel other pairs of electrons. This means that filled orbitals repel one another, which will come into play in just a bit. 

We see that some atoms have unpaired electrons in the same set of energetically equivalent, or degenerate, orbitals. We have already seen that two electrons can occupy a given atomic orbital (with the same values of n, i, and ntf) only if their spins are paired (have opposite values of Even with pairing of spins, however, two electrons that are in the same orbital repel each other more strongly than do two electrons in different (but equal-energy) orbitals. Thus, both theory and experimental observations (see the following Enrichment section) lead to Hund s Rule ... 

The hybrid orbital has electron density concentrated on one side of the nucleus, i.e. it has one lobe relatively larger than the other. Hence, the hybrid orbitals can form stronger bonds compared to unhybridized atomic orbitals because they can undergo more effective overlap. The hybrid orbitals repel each other and adopt a configuration that minimizes the electron repulsion. Hybridization is simply a mathematical model that is convenient for describing localized bonds. It is not a phenomenon that can be studied or measured. 

Electrons repel each other electrostatically, and the repulsion between an electron in one atomic orbital and an electron m... 

Valenee electrons are repelled by other eleetrons in valenee orbitals of the same carbon atom, a one-center, two-eleetron repulsion. These interactions are often parameterized with speetroseopic transition energies. 

How much can we bend this bond Well, the electrons of each ion occupy complicated three-dimensional regions (or orbitals ) around the nuclei. But at an approximate level we can assume the ions to be spherical, and there is then considerable freedom in the way we pack the ions round each other. The ionic bond therefore lacks directionality, although in packing ions of opposite sign, it is obviously necessary to make sure that the total charge (+ and -) adds up to zero, and that positive ions (which repel each other) are always separated by negative ions. 

The major features of molecular geometry can be predicted on the basis of a quite simple principle—electron-pair repulsion. This principle is the essence of the valence-shell electron-pair repulsion (VSEPR) model, first suggested by N. V. Sidgwick and H. M. Powell in 1940. It was developed and expanded later by R. J. Gillespie and R. S. Nyholm. According to the VSEPR model, the valence electron pairs surrounding an atom repel one another. Consequently, the orbitals containing those electron pairs are oriented to be as far apart as possible. 

To see why this splitting occurs, consider what happens when six ligands (e.g., HzO, CN-, NH3) approach a central metal cation along the x-, y-, and z-axes (Figure 15.9). The unshared electron pairs on these ligands repel the electrons in the d orbitals of the cation. 

We need to make another decision at carbon (Z = 6) does the sixth electron join the one already in the 2p-orbital or does it enter a different 2p-orbital (Remember, there are three p-orbitals in the subshell, all of the same energy.) To answer this question, we note that electrons are farther from each other and repel each other less when they occupy different p-orbitals than when they occupy the same orbital. So... 

The lobes of two d-orbitals on the same atom occupy markedly different regions of space. As a result, electrons in different d-orbitals are relatively far apart and repel one another only weakly. 

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