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However, an empirical mathematical relationship between the SR and the electronega-
tivity in Pauling Scale is suggested as:
χ
½
= 0.21SR + 0.77
(71)
where χ is the electronegativity in Pauling Scale.
It is also opined (Sanderson, 1952) that the SR of an atom is a measure of its elec-
tronegativity.
SR = χ
Sanderson
(72)
Sanderson found that halogen atoms bear a linear relationship between electroneg-
ativity and experimental electron affi nities. He also established a linear relationship
between acid/base strength and SR for a particular atom.
Sanderson defi ned the partial charge of the atom as a function of the difference
between the elemental electronegativity and that of the new electronegativity, the
equilibrium electronegativity. His original equation dealt with the difference between
the SR for the entire molecule and the SR for the atom for which the partial charge is
being calculated.
LEWIS ACID STRENGTH
Smith [52] complied a numerical scale of acid base character for binary oxides by
analogy with the Pauling Electronegativity Scale. For such oxides he proposed an em-
pirical acid base parameter “a.” Bratsch (1984, 1985, [48] point out that this parameter
can be used to predict the standard enthalpy of combination of binary oxide to form
oxo-salt as:
ΔH
0
comb
= -[a
A
-a
B
]
2
(73)
where a
A
and b
B
are the Smith acid base parameter.
Bratsch (1984, 1985, [48] suggested that the equalized χ
eq
in an oxide may be
estimated by N/∑[v/χ] where N is the number of atoms in the oxide formula, v is the
number of each element in the oxide formula, χ is the initial pre bound electronegativ-
ity of each element on the Pauling scale.
Bratsch (1984, 1985, [48] also gave a linear relationship between Smith oxide acid
base scale and Pauling electronegativity as:
a = m χ
eq
+ b
(74)
The potential change δ
0
on combined oxygen was given by Bratsch (1984, 1985,
[48] as follows:
δ
0
= (χ
eq
-χ
0
)/χ
0
(75)
Thereafter, Bratsch (1984, 1985, [48]) correlated the Smith's acid base parameter
with the partial charge as:
a = 33.7 δ
0
+ 9.2
(78)
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