Bonding electron domain

In the example above, the constraint is a chemical one, viz., the electronegativity difference between the ligands chlorine and fluorine that leads to a spatial constraint with respect to their bonding electron domains. 

Determine molecular geometry by counting only bonding electron domains to see arrangement of bonded atoms (trigonal pyramidal)... 

Each carbon is identical but now has three bonding electron domains that surroimd it. Therefore, the hybridization of each carbon atom is sp, and each carbon has local trigonal planar geometry with 120° angles. 

Bonding electron domain = shared valence electrons (2,4, or 6e ) localized between two core atoms 3 types Single Bond (1 pair, 2 electrons) Double Bond (2 pairs, 4 e ) Triple Bond (3 pairs, 6 e )... 

Non-bonding electron domain ( lone pair ) = pair of valence electrons (2 e ) not involved in a bond... 

E) Each molecule in Figure 1.2 has exactly one bonding electron domain. Identify it and... 

Use model materials to make a model of CH4 (methane). If you assembled it correctly, the four bonds (bonding electron domains) of your model will be 109.5° apart. 

When a ligand is more electronegative than the central atom, it draws the bonding electron density away from the central atom so that the space occupied by the bonding domain in the valence shell of the central atom decreases with increasing difference of electronegativity... 

VT > Ronald J. Gillespie, James N. MJI Spencer, and Richard S. Moog, "Demystifying Introductory Chemistry Part 2. Bonding and Molecular Geometry Without Orbitals-The Electron Domain Model," /. Chem. Educ., Vol. 73,1996,622-627. 

It is a small step from van der Waals, electron-domain models of the C—H bonds of, e.g., biphenyl, cyclohexane, or methane (Figs. 1—3), to molecular models in which to a first, and useful, approximation each valence-shell electron-pair is represented by a spherical, van der Waals-like domain 7h (Non-spherical domains may be useful for describing, e.g., lone pairs about atoms with large atomic cores, -electrons, and the electron-pairs of multiple bonds vide infra.)... 

A striking analogy exists between localized molecular orbital, electron-domain models of organic and other covalently bonded molecules (Figs. 3—8) and ion-packing models of inorganic compounds 47). 

The chief content of the isomorphism displayed in Table 1 is embodied in the phrase "electride ion . By introducing at the outset in the electronic interpretation of chemistry the wave-like character of electrons and the Exclusion Principle through the concept of van der Waals-like electron-domains or electride ions , whose sizes indicate the magnitudes of the electrons kinetic energies, whose impenetrability8) simulates, at least approximately, the operation of the Exclusion Principle, and whose charges yield within the framework of the model easily foreseeable effects, one transforms the complex treatment of the covalent bond in quantum mechanics into a simpler, if less precise, exercise in classical electrostatics. 

Fig. 11 is a drawing of a two-dimensional analogue of the electron-domain model of ethane. Large circles represent valence-shell electron-domains (superimposed on them are the valence strokes of classical structural theory). Plus signs represent protons of the "C—H bonds. The nuclei of the two carbon atoms are represented by small dots in the trigonal interstices of the electron-pair lattice. While these nuclei would not necessarily be in the centers of their interstices, exactly, it can be asserted that an (alchemical) insertion of the two protons on the... 

Fig. 13 is a drawing of electron-domain models of some Group VI hexafluorides. Open circles represent the electron-pairs of four of the six bonds to fluorine atoms in a Lewis, single-bond formulation of these molecules. Solid circles represent the atomic cores of oxygen, sulfur, selenium, tellurium, tungsten, and uranium (core radii, in hundreths of A, 9, 29, 42, 56, 62, and 80 2>, respectively). These hexafluorides are, in order, non-existent, extra-ordinarily unreactive, hydrolyzed slowly, hydrolyzed completely at room temperature in 24 hours, hydrolyzed readily, and hydrolyzed very rapidly. 

Fig. 19. Saturation of primary affinity. Two-dimensional representation of an electron-domain model of the formation of a conventional chemical bond the reaction of a Lewis base (NHg) with a relatively strong Lewis acid (BH3).

A drawing of a two-dimensional, electron-domain model of a conventional Lewis lone pair is shown in Fig. 23. The lone pair and bonding pairs are structurally equivalent they have identical van der Waals envelopes. Such seems to be nearly the case for lone pairs in the valence-shells of small-core, non-octet-expanding atoms (carbon, nitrogen, oxygen and fluorine). 

Multicenter Bonding. While the valence stroke of classical structural theory is for many purposes a useful representation of an electron-domain created by the fields of two atomic cores (for every line-segment... 

Fig. 30 A—C. The Berry mechanism for electron-pair-coordination-number 5. (A) Trigonal bipyramidal coordination. Ligands bonded through shaded electron-domains are in axial positions. (B) Tetragonal pyramidal coordination. A slight distortion of structure A. (C) Trigonal bipyramidal coordination. A slight distortion of structure B. Ligands bonded through shaded electron-domains are now in equatorial positions...

---