INO-15

Ionic potential φ = Z/r

φ = Z / r. Polarising power of a cation.

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BondingCartledge

Governing equation

\varphi=Z/r

where

Z: Charge (—)
r: Ionic radius (Å)
\varphi: Ionic potential (\mathrm{\AA}^{-1})

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-15 — Ionic potential φ = Z/r) is the form associated with Cartledge. Working symbols: $Z$ , $r$ $\rightarrow$ $\varphi$ . High φ (small, highly charged) polarises anions and leans covalent — Fajans.

Purpose

Purpose: compute

\varphi

from

Z

r

in Inorganic chemistry via

\varphi=Z/r

φ = Z / r. Polarising power of a cation. 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 = 3.000\,\mathrm{—}

r = 0.640\,\mathrm{Å}

, the governing relation

\varphi=Z/r

yields

\varphi = 4.688\,\mathrm{mathrmAA^-1}

. r in Å, Z the formal charge. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Charge Z3 —Ionic radius r0.64 Å

Outputs

Ionic potential \varphi4.688 \mathrm{\AA}^{-1}

Reading speed

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Narration of this film

r in Å, Z the formal charge.

High φ (small, highly charged) polarises anions and leans covalent — Fajans.

Reading speed

Watch on YouTube