Electronegativity Rochow

Later methods, especially that of Gordy (1955), and later Allred and Rochow (1958) make use of screening constants of the electron strucmre for the nuclear charge of each atom. This determines die attraction between the nucleus of the atom and an electron outside the normal electron complement, and is die effective nuclear charge. The empirical equation for the values of electronegativity obtained in this manner by Allred and Rochow is... 

Covalent radii and electronegativity values from Ref. 10. AEN is the difference in electronegativity between the two elements using the Allred-Rochow scale. 

Covalent radii and electronegativity values (Allred-Rochow) are abstracted from Huheey, J. E. Keiter, E. A. Keiter R. L. Inorganic Chemistry, 4th ed. Harper Row New York, 1993 pp. 187 and 292. 

Covalent Radii and Electronegativities (Allred-Rochow) of Carbon s First-Row Neighbors in the Periodic Table... 

Table 1.2 Electronegativity Values According to Allred and Rochow...

If a property is as important as is electronegativity, it is not surprising that a large number of approaches have been taken to provide measures of the property. Although we have already described two approaches, we should also mention one additional method. Allred and Rochow made use of the equation... 

In this equation, Z is the effective nuclear charge, which takes into account the fact that an outer electron is screened from experiencing the effect of the actual nuclear charge by the electrons that are closer to the nucleus (see Section 2.4). In principle, the Allred-Rochow electronegativity scale is based on the electrostatic interaction between valence shell electrons and the nucleus. 

Table 3.9. A comparison of Pauling (xa

Figure 3.17 Electronegativities xA for elements of groups 13-17, comparing natural values (circles, solid lines) with Pauling (triangles, dashed lines) and Allred-Rochow (squares, dotted lines) values.

Fe3+. There are several ways of defining electronegativity, the simplest being that of Allred and Rochow (1958), which calculates the force experienced by the outer electron from the nucleus using Coulomb s law of electrical attraction ... 

Allred, A. L. and Rochow, E. G. (1958). A scale of electronegativity based on electrostatic force. Journal of Inorganic and Nuclear Chemistry 5 264-268. 

Figure 1. a-SCS values in substituted methanes (CH3X) plotted against AUred-Rochow electronegativities (X). 

Figure 3. fi-SCS(X) in 2-substituted adamantanes 25 plotted against Allred-Rochow electronegativities (X). 

A number of useful properties of the Group 1 elements (alkali metals) are given in Table 8. They include ionization potentials and electron affinities Pauling, Allred-Rochow and Allen electronegativities ionic, covalent and van der Waals radii v steric parameters and polarizabilities. It should be noted that the ionic radii, ri, are a linear function of the molar volumes, Vm, and the a values. If they are used as parameters, they cannot distinguish between polarizability and ionic size. 

Figure 5.20 Table of the binary hydrides and the Allred-Rochow electronegativity [26], Most elements react with hydrogen to form ionic, covalent or metallic binary hydrides.

Table 8. Allred-Rochow electronegativity and magnetic behavior of NiL4X complexes )...

Symbol Sb atomic number 51 atomic weight 121.75 Group VA (group 15) element atomic radius 1.41A ionic radius 86 + 0.76A covalent radius 1.21A electronic configuration [Kr] 4di°5s25p3 a metalloid element electronegativity 1.82 (Allred-Rochow type) valence states +5, +3, 0 and -3 isotopes and natural abundance Sb-121 (57.3%), Sb-123 (42.7%)... 

Symbol As atomic number 33 atomic weight 74.922 covalent radius AsS+ 1.2 lA electron configuration [Ar] 4s23di°4p3 a Group VA (Group 15) metalloid element electronegativity 2.20 (Allred-Rochow type) principal valence states, -1-5, +3, 0, and -3 stable isotope As-75. 

The now generally accepted scale of electronegativity was derived by Allred and Rochow and is known by their names. It is based on the concept that the electronegativity of an element is related to the force of attraction experienced by an electron at a distance from the nucleus equal to the covalent radius of the particular atom. 

Figure 1.7 The Allred-Rochow electronegativity coefficients of the main group elements of the 2nd, 3rd, 4th and 5th periods...

Table 5.6 Bond length and bond angle data for some compounds with the formula EL,. The differences between the electronegativity coefficients (Allred-Rochow) of the elements are also given...

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