Orbital regions

The structure of ethylene and the orbital hybridization model for its double bond were presented m Section 2 20 and are briefly reviewed m Figure 5 1 Ethylene is planar each carbon is sp hybridized and the double bond is considered to have a a component and a TT component The ct component arises from overlap of sp hybrid orbitals along a line connecting the two carbons the tt component via a side by side overlap of two p orbitals Regions of high electron density attributed to the tt electrons appear above and below the plane of the molecule and are clearly evident m the electrostatic potential map Most of the reactions of ethylene and other alkenes involve these electrons... 

Orbital Region of space in which there is a high probability of finding an electron within an atom, 141 band theory and, 654—655 hybrid, 186,187 relation to ligand, 418... 

Figure 6.2 Polar graphs of the hydrogen 2p atomic orbitals. Regions of positive and negative values of the orbitals are indicated by + and — signs, respectively. The distance of the curve from the origin is proportional to the square of the angular part of the atomic orbital.

Reim, M. The results of ischemia in chemical injuries. Eye 6, 376-380 (1992) Reim, M., Kuckelkom, R. Chemical and thermal lesions in the orbital region. BuU. Soc. Beige Ophtalmol. 245, 21-28 (1992) Reim, M., Teping, C. Surgical procedures in the treatment of most severe eye burns. Acta. Ophthalmol. Scand. 67, 47-54 (1989). 

Atomic orbitals Regions of space around the nucleus that have a nonzero probability of containing an electron in a specific energy state. 

Fig. 7. A qualitative MO scheme for ferrocene and other first-row transition-metal metallocenes. The inset highlights the ordering of the (/-orbitals in the frontier orbital region and provides the definition for A, and A (see the text).

Figure 17 shows the present-day model of the atom, which takes into account both the particle and wave properties of electrons. According to this model, electrons are located in orbitals, regions around a nucleus that correspond to specific energy levels. Orbitals are regions where electrons are likely to be found. Orbitals are sometimes called electron clouds because they do not have sharp boundaries. When an orbital is drawn, it shows where electrons are most likely to be. Because electrons can be in other places, the orbital has a fuzzy boundary like a cloud. 

The present-day model of the atom, in which electrons are located in orbitals, is also known as the quantum model. According to this model, electrons within an energy level are located in orbitals, regions of high probability for finding a particular electron. However, the model does not explain how the electrons move about the nucleus to create these regions. 

Occasionally, it is advantageous to add one further level of complexity to the calculation diffuse functions. Here, heavy atoms are given access to diffuse s- and p-type functions so that their more diffuse orbital regions are considered in calculations. This has relevance for supramolecular chemists interested in anion recognition as diffuse and polarizable orbitals associated with halides are likely to be involved in anion recognition and binding. In Pople notation, these basis sets are denoted by a -I- sign as in 6-311-l-G. ... 

Scheme 2 Frontier Orbital Region of C60 from MS-Xa Results, Showing Transitions Available to C60 and its Derivatives C60 and C60 -...

Scheme 3 Frontier Orbital Region of C O Mapped by Experimental Results.

---