The Electronegativity of Atoms

To understand the nature of the intermolecular forces, we must first learn a new concept, called electronegativity (EN), which is defined as follows  

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Pauling s electronegativity difference, where represents the electronegativity of atom X. 

In the simple bond charge model for the diatomic AB, the natural definition of the electronegativity of atom A, in the final molecule after charge transfer, has the form... 

With an electronegativity table, establishing the ionic or covalent nature of the bond between two atoms is just a matter of simple subtraction. However, there is more to understanding the chemical bond than just knowing the electronegativity of atoms. Several other bond variations will be covered in the next chapter. 

Engl. TransL), 296, 440 (1987). Scheme for the Calculation of the Electronegativities of Atoms in a Molecule in the Framework of Sanderson s Principle. 

Organic molecules often have polar covalent bonds as a result of unsym-metrical electron sharing caused by difterences in the electronegativity of atoms. For example, a carbon-chlorine bond is polar because chlorine attracts the shared electrons more strongly than carbon does. Carbon-hydrogen bonds are relatively nonpolar. Many molecules as a whole are also polar owing to the cumulative effects of individual polar bonds and electron lone pairs. The polarity of a molecule is measured by its dipole moment, p. 

The electronegativity of hydrocarbons is half the sum of the ionization potential plus the electron affinity, the Mulliken definition of the electronegativity of atoms. In the simplest approximation the electronegativity is constant and equal to the work function of graphite. This gives the relationship ... 

Xie, Sun et al, 1995]. For example, Sanderson group electronegativity ESG is calculated as the geometric mean of the electronegativities of atoms belonging to the considered group [Sanderson, 1983] ... 

The electronegativity of atoms linked directly to oxygen atoms has major influence on the chemical shifts of O. The substituents at various positions of the ring also have influence to some... 

The electronegativity of atoms and the polarity, length, and energy of bonds determine acid strength. 

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