Time Evolution of the Electronegativity - Modern Trends in Chemistry and Chemical Engineering - page 18

Nagle's Scale of Electronegativity [95]
Nagle's [95] Scale of electronegativity is based on atomic polarizability. The static
electric dipole polarizability or simply polarizability is an experimentally measurable
property of an isolated atom. The valence electron density is a parameter which can
define and measure the electronegativity of an atom. Nagle found that the cube root
of this ratio of the number of valence electrons divided by the polarizability, (n/α) 1/3 ,
can be used as a measure of electronegativity for all s- and p-block elements (except
the noble gases). The value fits well with the electronegativities in Pauling Scale and
the correlation yields:

χ = 1.66 (n/α)1/3 + 0.37 (65)

Ghosh and Gupta [51] also proposed a simple relation between χ and α as:

χ = a(1/α) 1/3 + b (66)

where a and b are two constants for a given period of the periodic table.

Zheng and Li's Scale of Electronegativity (1990)
Based on the average nuclear potential of the valence electrons, Zheng and Li (1990)
discovered a new method for the determination of the effective nuclear charge Z eff
and, considering the atomic electronegativity scale of Mulliken, they defined electro-
negativity as the ratio of Z eff and the mean radius, <r> nl of the outermost electron of
an atom:

χ M = (I + A)/2 = Z eff / <r> nl (67)

Ghosh's Scale of Electronegativity [50]
Considering the periodic behavior of the electronegativity and the atomic radius,
Ghosh [50] put forward a simple equation for evaluating atomic electronegativity as:

χ = a (1/r abs ) + b (68)
where χ is electronegativity and r abs is the absolute radii of the atoms, a and b are
two constants.

Li and Xue's Scale of Ionic Electronegativity [96]
Li and Xue [96] proposed an electronegativity scale for the elements in different va-
lence states and with the most common coordination number in terms of effective
ionic potential. They defined the effective ionic potential as
φ = n*(I/R) 1/2 /r (69)
where I m = R(Z eff /n*) is the ultimate ionization energy, n* is the effective principal
quantum number and R (in eV) is the Rydberg constant and r i is the ionic radius.
They proposed that electronegativity of an ion is proportional to the effective ionic
potential and proposed a linear relationship between the ionic electronegativity and the
effective ionic potential as:

χ ion = a φ + b (70)