 Bond polarization

ID: bond-polarization

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Bond polarization by

Codex  0 Created 2026-10-13 Updated 2026-10-20

Bond polarization is unequal sharing of electron density across a chemical bond. An electronegativity difference is a heuristic for its direction and tendency, not a unique partial atomic charge.

A simple two-site model makes the notation explicit. Represent each site by effective positive electric charge

+ e

, and allocate expected electron populations

1 - s

to

A

and

1 + s

to

B

, with

0 \leq s < 1

. Here

e

is the elementary charge; these effective sites omit the internal structure of real chemical atoms. Subtraction gives

q_{A} = e - e (1 - s) = se, q_{B} = e - e (1 + s) = - se, q_{A} + q_{B} = 0.

For the stipulated illustration

s = 0.35

, the populations are

0.65

and

1.35

, and the effective partial atomic charges are

+ 0.35 e

and

- 0.35 e

. Fractional expected populations do not split an individual electron into pieces. The total population remains two, and the pair remains neutral. No formula connecting

s

to

Δ χ

has been assumed; many electron density distributions and partitioning conventions can share one qualitative electronegativity ordering.

Figure 1.
Stipulated two-site bond polarization: expected electron populations, effective partial atomic charges, and opposite chemical and physical arrow conventions
. Original model with $s = 0$ and $s = 0.35$ , effective positive site charges $+ e$ , and two expected electrons in total. The population bars are bookkeeping weights, not a measured electron density map. Arrow lengths illustrate direction only; no empirical electronegativity values or charge calibration are implied. Details.

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