\[\%\text{离子性} = \frac{\mu_\text{实测}}{e\,d}\times100\%,\qquad \%\text{离子性}_\text{鲍林} = \left(1 - e^{-(\Delta\chi)^2/4}\right)\times100\%\]\[\%\text{ionic character} = \frac{\mu_\text{measured}}{e\,d}\times100\%,\qquad \%\text{ionic character}_\text{Pauling} = \left(1 - e^{-(\Delta\chi)^2/4}\right)\times100\%\]
含义Meaning
把实测偶极矩与完全转移一个电子时的偶极矩比较，或由电负性差按鲍林经验式估算。Δχ ≈ 1.7 时约 50%，常作为离子键与共价键的粗略分界。
Compare the measured dipole with that for full electron transfer, or estimate from the electronegativity difference (Pauling). Δχ ≈ 1.7 gives ~50 %, a rough ionic/covalent divide.
符号说明Symbols
| 符号Symbol | 含义 Meaning | 单位 Unit |
|---|---|---|
| \(\Delta\chi\) | 鲍林电负性差Pauling electronegativity difference | 1 |
| \(d\) | 键长bond length | m |
推导Derivation
完全离子：μ = ed；实测值与之比即为“离子性”。
Fully ionic: μ = ed; the ratio gives ionic character.
鲍林把卤化氢的离子性与 Δχ 拟合，得到指数形式经验式。
Pauling fitted hydrogen halides to the exponential form.
适用条件与局限Assumptions & limitations
离子性没有唯一的定义；偶极矩还受极化、孤对影响（如 CO 偶极矩很小且方向“反常”）。
No unique definition; dipoles include polarisation and lone-pair effects (CO is anomalous).