INO-02

Allred–Rochow electronegativity

χ_AR = 0.359 Zeff / r² + 0.744 with r in Å.

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BondingAllred–Rochow

Governing equation

\chi_{\mathrm{AR}}=0.359\,Z_{\mathrm{eff}}/r^2+0.744

where

Z_{eff}: Effective charge (—)
r: Covalent radius (Å)
\chi_{AR}: Electronegativity (—)

Lecture brief

Historical brief

Pauling and Allred–Rochow electronegativity, Kapustinskii lattice energy, CFSE and Goldschmidt radii organise the periodic solid. The sheets predict bond character and crystal packing. This sheet (INO-02 — Allred–Rochow electronegativity) is the form associated with Allred–Rochow. Working symbols: $Z_{eff}$ , $r$ $\rightarrow$ $\chi_{AR}$ . A force-on-valence-electron scale. Complements Pauling when thermochemistry is missing.

Purpose

Purpose: compute

\chi_{AR}

from

Z_{eff}

r

in Inorganic chemistry via

\chi_{\mathrm{AR}}=0.359\,Z_{\mathrm{eff}}/r^2+0.744

χ_AR = 0.359 Zeff / r² + 0.744 with r in Å. Use it when a real inorganic chemistry question must be answered in SI before a code check.

Live realistic example

In symbols

Live case. Given

Z_{eff} = 4.350\,\mathrm{—}

r = 0.770\,\mathrm{Å}

, the governing relation

\chi_{\mathrm{AR}}=0.359\,Z_{\mathrm{eff}}/r^2+0.744

yields

\chi_{AR} = 3.38\,\mathrm{—}

. Covalent radius in Å, Slater Zeff. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Effective charge Z_{eff}4.35 —Covalent radius r0.77 Å

Outputs

Electronegativity \chi_{AR}3.38 —

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Narration of this film

Covalent radius in Å, Slater Zeff.

A force-on-valence-electron scale. Complements Pauling when thermochemistry is missing.

Reading speed

Watch on YouTube