Electronegativity (Allred-Rochow): group 8
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 ΧAR
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 = e2Zeff/r2
- r is the distance between the electron and the nucleus (covalent radius)
- e is the charge on an electron
- eZeff is the charge effective at the electron due to the nucleus and its surrounding electrons
The quantity Zeff/r2 correlates well with Pauling electronegativities and the two scales can be made to coincide by expressing the Allred-Rochow electronegativity as:
ΧAR = 0.744 + 0.359Zeff/r2
- 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.
You can buy periodic table posters, mugs, T-shirts, fridge magnets, games, molecular models, and more at the WebElements shop
- Search WebElements
- Search Chemistry Web
- Essential data
- The elements round us
- Compounds: halides, oxides, sulfides, hydrides, and complexes; lattice energies; and reduction potentials
- Reactions of : reactions with air; water; halogens; acids; and bases
- Electronegativities: Pauling; Sanderson; Allred-Rochow; Mulliken-Jaffe; and Allen
- Bond enthalpies of diatomic species
- Lattice energies: oxides and halides
- Element properties
- Physics properties: boiling point; melting point; density; and molar volume; thermal conductivity; and electrical resistivity; bulk modulus; critical temperature; superconductivity temperature; hardness (mineralogical, Brinell, and Vickers); linear expansion coefficient; Poisson's ratio; reflectivity; refractive index; rigidity modulus; Young's modulus; and velocity of sound
- Crystal structure
- Thermochemistry: enthalpies of atomisation, fusion, and vaporisation, thermodynamic properties
- Atom properties
- Electronic properties: electronic configuration; term symbol; electron affinity; ionisation energies; and atomic spectra
- Atom sizes: atomic radii; Shannon and Pauling Ionic radii; covalent radius; metallic radius; element bond length; and Van der Waals radius
- Electron shell properties: effective nuclear charge; electron binding energies; and valence orbital radii maxima
- Nuclear properties
Search Chemistry Web