Percent Ionic Character Calculator — Bond Polarity (Pauling)
Enter the Pauling electronegativity values of two bonded atoms to calculate the percent ionic character of the bond, the electronegativity difference (ΔEN), and the classification as nonpolar covalent, polar covalent, or ionic.
Polar covalent (5–50%)
- 1
Electronegativity difference (ΔEN)
|3.44 − 2.2| = 1.24 - 2
ΔEN²
1.24 × 1.24 = 1.5376 - 3
Exponent (−0.25 × ΔEN²)
−0.25 × 1.5376 = -0.3844 - 4
e raised to exponent
e^(-0.3844) = 0.680859 - 5
Percent ionic character
(1 − 0.680859) × 100 = 31.9
How does this calculator work?
Percent ionic character = (1 − e^(−0.25 × ΔEN²)) × 100, where ΔEN is the absolute electronegativity difference between two bonded atoms (Pauling scale). < 5 % = nonpolar covalent; 5–50 % = polar covalent; > 50 % = ionic. Example: O–H (ΔEN = 1.24) ≈ 39 % ionic.
Formula
How this is calculated
The Pauling formula quantifies how ionic a chemical bond is based on the difference in electronegativity (ΔEN) between the two bonded atoms. A purely covalent bond has ΔEN = 0 (electron sharing is equal), while a fully ionic bond has ΔEN so large that one atom effectively captures the shared electron. The exponential formula — derived empirically by Pauling from thermochemical data — maps ΔEN smoothly onto a 0–100 % ionic scale.
Three ranges are conventionally used to classify bonds: less than 5 % ionic character (ΔEN < ~0.4) is considered nonpolar covalent; 5–50 % (ΔEN ~0.4–1.7) is polar covalent; above 50 % (ΔEN > ~1.7) is ionic. For example, an O–H bond (ΔEN = 1.24) is about 39 % ionic — polar covalent — explaining the dipole moment of water. NaCl (ΔEN = 2.23) is about 70 % ionic.
Limitations: the Pauling scale electronegativity values are empirically derived averages for an element in its typical oxidation state; actual bond polarity in a molecule depends on geometry, resonance, inductive effects, and substituents not captured by this single-pair formula. The formula should be treated as a useful approximation rather than an exact prediction.
Frequently asked questions
The traditional rule of thumb is ΔEN ≥ 1.7 (roughly 50 % ionic character) to classify a bond as ionic. However, this cutoff is a guideline, not a strict law. Many bonds in the 40–60 % ionic-character range have significant character of both types. The Pauling scale gives ΔEN = 1.7 as approximately corresponding to 50 % ionic character.
Standard Pauling electronegativities are tabulated in every inorganic and physical chemistry textbook, and in NIST and WebElements databases. Common values: F = 3.98, O = 3.44, N = 3.04, Cl = 3.16, C = 2.55, H = 2.20, Na = 0.93, Li = 0.98, Cs = 0.79. The hint text under each field lists several reference values.
Not necessarily. Bond strength (bond dissociation energy) depends on both ionic and covalent contributions plus orbital overlap. Highly ionic bonds (like NaCl) are strong in the crystal lattice but weaker in the gas phase. Highly covalent bonds (like C≡N) can be extremely strong through orbital overlap. Percent ionic character describes polarity, not strength.
Also known as
TG we-Calculate Editorial Team. (2026). Percent Ionic Character Calculator — Bond Polarity (Pauling) [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/percent-ionic-character-calculator
TG we-Calculate Editorial Team. "Percent Ionic Character Calculator — Bond Polarity (Pauling)." TG we-Calculate. 2026. https://we-calculate.com/calculator/percent-ionic-character-calculator.
TG we-Calculate Editorial Team, "Percent Ionic Character Calculator — Bond Polarity (Pauling)," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/percent-ionic-character-calculator
@misc{wecalculate_percent_ionic_character_calculator, title = {Percent Ionic Character Calculator — Bond Polarity (Pauling)}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/percent-ionic-character-calculator}}, year = {2026}, note = {TG we-Calculate} }
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