Electronegativity (Allred-Rochow)

Allred and Rochow suggest a scale of electronegativity based upon the electrostatic force of attraction between the nucleus and the valence electrons. The values expressed here are converted to the Pauling scale (see below). The Allred-Rochow electronegativity is often denoted as Χ_AR

Units

Pauling scale

Notes

Most values are taken from reference 1. Additional values for elements 40-46 and 58 onwards are contained within reference 2. Values for elements 95-102 are estimates. Values for Group 18 elements are taken from reference 3. Essentially similar data for Allred-Rochow electronegativities are given in references 4 and 5, as well as many text books.

The force of attraction is given by:

force = e²Z_eff/r²

where

r is the distance between the electron and the nucleus (covalent radius)
e is the charge on an electron
eZ_eff is the charge effective at the electron due to the nucleus and its surrounding electrons

The quantity Z_eff/r² correlates well with Pauling electronegativities and the two scales can be made to coincide by expressing the Allred-Rochow electronegativity as:

Χ_AR = 0.744 + 0.359Z_eff/r²

You can look at visual representations of the various electronegativity scales using the following links.

Literature sources

A.L. Allred and E.G. Rochow, J. Inorg. Nucl. Chem., 1958, 5, 264.
E.J. Little and M.M. Jones, J. Chem. Ed., 1960, 37, 231.
J.E. Huheey, E.A. Keiter, and R.L. Keiter in Inorganic Chemistry : Principles of Structure and Reactivity, 4th edition, HarperCollins, New York, USA, 1993.
W.W. Porterfield in Inorganic chemistry, a unified approach, Addison Wesley Publishing Co., Reading Massachusetts, USA, 1984.
A.M. James and M.P. Lord in Macmillan's Chemical and Physical Data, Macmillan, London, UK, 1992.

Explore the element of your choice through this periodic table.
1	2		3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18
1 H			2 He
3 Li	4 Be		5 B	6 C	7 N	8 O	9 F	10 Ne
11 Na	12 Mg		13 Al	14 Si	15 P	16 S	17 Cl	18 Ar
19 K	20 Ca		21 Sc	22 Ti	23 V	24 Cr	25 Mn	26 Fe	27 Co	28 Ni	29 Cu	30 Zn	31 Ga	32 Ge	33 As	34 Se	35 Br	36 Kr
37 Rb	38 Sr		39 Y	40 Zr	41 Nb	42 Mo	43 Tc	44 Ru	45 Rh	46 Pd	47 Ag	48 Cd	49 In	50 Sn	51 Sb	52 Te	53 I	54 Xe
55 Cs	56 Ba	*	71 Lu	72 Hf	73 Ta	74 W	75 Re	76 Os	77 Ir	78 Pt	79 Au	80 Hg	81 Tl	82 Pb	83 Bi	84 Po	85 At	86 Rn
87 Fr	88 Ra	**	103 Lr	104 Rf	105 Db	106 Sg	107 Bh	108 Hs	109 Mt	110 Ds	111 Rg	112 Cn	113 Nh	114 Fl	115 Mc	116 Lv	117 Ts	118 Og

*Lanthanoids	*	57 La	58 Ce	59 Pr	60 Nd	61 Pm	62 Sm	63 Eu	64 Gd	65 Tb	66 Dy	67 Ho	68 Er	69 Tm	70 Yb
**Actinoids	**	89 Ac	90 Th	91 Pa	92 U	93 Np	94 Pu	95 Am	96 Cm	97 Bk	98 Cf	99 Es	100 Fm	101 Md	102 No

Explore the element of your choice through this periodic table.

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

*Lanthanoids

**Actinoids

100

101

102