According to the Bohr energy model
E = - Z2me4/8n2h2ɛ02 = - RZ2/n2
Zhang obtained the effective principal quantum number n* and the effective nuclear charge Z* from the ionization energy by spectroscopy [1, 2]:
Z*=n*( Iz /R)½
Then he proposed the first scale of the orbital electronegativity in valence states corresponding all electron configurations from 1s to nf in 1981:
Xz = 0.241 n*(Iz /R)½ /r2 + 0.775
where Iz is the ultimate ionization energy for outer electrons of the s,p,d and f orbital of the atom. R is the Rydberg constant, R = 2p2µ42e4/h2 = 13.6eV, h is Planck’s constant and n*( Iz /R)½ is the effective nuclear charge Z* felt by the valence electron at the covalent boundary r.
Being composed of the various quantum parameters of atomic orbital Iz(s,p,d,f), n*, Z*, rc , rc-1, n*rc-1, based on spectroscopy, Zhang electronegativity formed a Method of the multiple-functional prediction which can explain chemical observations of elements of all orbital electron configurations from 1s to nf, and has the more versatile and exceptional applications than the other electronegativity scales and molecular properties, including the σ-bond, the linear or nonlinear combinations of ionic bond and covalent bond, the orbital spatial overlaps and the orbital spatial crosslinks. However, the Pauling electronegativity scales  are only one datum per element that not based on the above spectroscopic electron orbital configuration but based on a limited situation of the linear difference of the thermochemical energy of two elements (H and Cl) extended to the all elements. And so that sometime has misled to the opposite wrong results [4, 5]. The major problem is that the attraction for an electron is not in an unambiguous valence [1, 2, 6-9].
In the effort to derive molecular information from atomic properties a criterion of three types of atomic properties were proposed by Bergmann-Hinze : a) those that can be determined directly by spectroscopy, ionization potentials are strongly suggested, b) those based on theoretical concepts, the quantum mechanics should be correlated, and c) those that can be assigned to the atoms interacting in molecules, covalent radii are preferred. It is a criterion for evaluating all electronegativity and molecular properties. Zhang electronegativity  is best up to criterion.
Cherkasov et al.reriewed  that the current state of the problem is that the electronegativity is not an interpretation of the definite and unambiguous valence state. Although Allred-Rochow Electro negativity is an attraction that meets the Pauling’s definition, it still is not an unambiguous valence state. Allred-Rochow Electronegativity original only has 44 elements and are from the arbitrarily estimated Slater rule . For the other 59 elements the Slater’s Rules fail to correlate with ionization energy data [1, 2, 12]. A number of textbook writers have used the extended results of electrostatic force but have referenced the Allred-Rochow paper .
On Zhang electronegatiavity system, Cherkasov et al. reviewed: that “the force acting on an electron (and hence electronegativity) can be determined within the framework of the inverse quadratic dependence on the radius rc using the ionization potential of the valence electron Iz and the effective principal quantum number n*.
According to the conclusion by Cherkasov et al., Zhang electronegativity is not only a quantum spectroscopic “force” but also is the one solved the current problem of the ambiguous valence state.
Therefore, over the 30 year, Zhang electronegativity has been the best encompassed electronegativity  and widely quantitatively used [4-9,13-15]. Here we needn’t to retrieve and improve the electronegativity by ionocovalency, which is correlated with the quantum potential recently [16, 17].
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