Allred-Rochow electronegativities

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. 

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

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 )...

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

The first element, hydrogen, has an Allred Rochow electronegativity coefficient of 2.1, and an electronic configuration Is1. The atom may lose the single electron to become a proton, which exists in aqueous solutions as the hydroxonium ion, H30+(aq), in which the proton is covalently bonded to the oxygen atom of a water molecule. The ion is hydrated, as is discussed extensively in Chapter 2. The reduction of the hydrated proton by an electron forms the reference standard half-reaction for the scale of reduction potentials ... 

The very negative Ln t + /Ln potentials are consistent with the electropositive nature of the lanthanide elements their Allred-Rochow electronegativity coefficients are all 1.1 except for europium, which has a value of 1.0. The lighter elements of Group 3, Sc and Y, both have electronegativity coefficients of 1.3. The nearest p-block element to the lanthanides in these properties is magnesium (Mg2+/Mg) = -2.37 V, and its electronegativity coefficient is 1.2. 

Alkyl complexes, 655-657 Alkyne complexes, 662-666 Allen, L. C., 191 Allred-Rochow electronegativities, 190, 195 Ally complexes, 666-668 Alternation of electronegativities, 884-885... 

Fig. 4.5. Allred-Rochow electronegativities xA of Main Group atoms, plotted against Period n.

The relationship that gives Allred-Rochow electronegativities on the Pauling scale is... 

Several other approaches have been proposed for determining electronegativities but only two of these will be mentioned here. Mullikcn proposed an electronegativity scale based on taking x be the average of the E and Z values of the element. Allred and Rochow proposed that eleetronegativity be defined as the force exerted by the nucleus on the valence electrons,. so that the Allred-Rochow electronegativity. can be calculated from the... 

It is very often necessary to estimate values of electrical-effect parameters for groups for which no measured values are available. This is of particular importance with regard to substituents in which arsenic, antimony or bismuth is the central atom. It has long been known the electrical-effect parameters of substituents X whose structure can be written as MZ are a function of the electrical effect of the Z when M is held constant In later work it was shown that when Z is held constant and M is allowed to vary, the substituent constant is a function of the Allred-Rochow electronegativity of M, Xm and the number of Z groups, n. It has been shown that when both Z and M vary, values for all groups of the type X = MZ Z Z are given by an equation of the form ... 

Equations 24, 26 and 27 apply to M Z =M Z and M =M Z groups. They may be used to calculate substituent constants for both frons-vinylene and vinylidene groups. For these groups the value of xm Xm > Allred-Rochow electronegativity of carbon is 2.50 and the value of the number of bonds in the M —bond, is 1. Thus, equations 24, 26 and 27 simplify to ... 

Allred-Rochow electronegativity is proportional to Z g/r2, where Zeff is the effective nuclear... 

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