Time Evolution of the Electronegativity - Modern Trends in Chemistry and Chemical Engineering - page 20

They proposed the electronegativity as:
χ = η (72)
To justify their hypothesis that “if one measures hardness, the electronegativity
is simultaneously measured and vice-versa” to compute some descriptors of the real
word like the dipole moment, bond distance, reaction surface, and so forth. [17-22].
COMMON PROPOSITION REGARDING ELECTRONEGATIVITY
A search of literature [25] reveals that a good number of workers converge to number
of common proposition regarding electronegativity:
1. It is a periodic property.
2. It is an intrinsic atomic property which is associated with shell structure of
atoms and arises from the screened nuclear charge.
3. It is a global property of atoms, molecules, and ions.
4. It is a property which has to be measure in energy units.
5. It is an empirical quantity.
6. Electronegativity is a conceptual entity, not an experimentally observable
property.
7. As there is no quantum mechanical operator for electronegativity, the quantum
mechanical evaluation of electronegativity is ruled out [17-20, 22, 40, 41).
There are certain rules for a reasonable scale of electronegativity [14, 48, 99],
namely,
1. Electronegativity scales must have free atom definition.
2. Electronegativity should be expressed in energy unit.
3. Contraction of the main transition group elements must be transparent.
4. Electronegativity values of noble gas elements must be highest in each period.
5. Electronegativity scales must satisfy the Silicon rule--all metals must have
electronegativity values that are less than or equal to that of Si.
6. Electronegativity scales must satisfy the Carbon rule--the electronegativity
value of C has to be greater than, or at least equal to, that of H.
7. Existence of the metalloid band in the computed electronegativity data of the
elements: The six metalloid elements B, Si, Ge, As, Sb, and Te that separate
from the non-metals have electronegativity values, which do not allow over-
laps between metals and non-metals.
8. Electronegativity scales should quantify the Van Arkel-Ketelaar triangle.
9. A high precision is necessary for each scale.
10. In binary compounds, the electronegativity of the constituent atoms clearly
quantifies the nature of bonds.
11. Electronegativity scales must be compatible with the elementary quantum
concepts such as shell structure, quantum numbers, and energy levels which
describe the electronic structure of atoms.