Electronegativity Calculator

Look up electronegativity values (Pauling scale) and calculate bond polarity. Determine ionic vs covalent character, percent ionic character, and predict bond type from electronegativity difference.

⚗️ Bonding📐 Bond polarity from ΔEN🧪 Chemistry
Electronegativity of atom 1 (Pauling)
Electronegativity of atom 2 (Pauling)

Common: H=2.20, C=2.55, N=3.04, O=3.44, F=3.98, Cl=3.16, Na=0.93, K=0.82

Please enter valid values.

Formula & Reference

VariableSymbolFormulaUnits
Electronegativity Calculator—Bond polarity from ΔENPauling units

Step-by-Step Examples

Example 1
HF Bond

H: EN=2.20. F: EN=3.98.

  • dEN = |3.98-2.20| = 1.78
  • % ionic = (1-e^(-0.25 x 1.78^2)) x 100
  • = (1-e^-0.793) x 100 = (1-0.452) x 100 = 54.8%
  • Type: Ionic (dEN > 1.7)
✓ HF: dEN=1.78, 54.8% ionic character
Example 2
HCl Bond

H: 2.20, Cl: 3.16.

  • dEN = 0.96
  • % ionic = (1-e^-0.231)*100 = 20.6%
  • Type: polar covalent
✓ HCl: 20.6% ionic, polar covalent
Example 3
C-H Bond

C: 2.55, H: 2.20.

  • dEN = 0.35
  • Type: nonpolar covalent (dEN < 0.5)
  • C-H bonds considered nonpolar in organic chemistry
✓ C-H: essentially nonpolar covalent

Real-World Applications

⚗️
Organic Chemistry
C-H (dEN=0.35) nonpolar. C-O (dEN=0.89) polar. Determines solubility and reactivity.
💊
Drug Design
Polarity determines membrane permeability. Nonpolar drugs cross membranes more easily.
🌍
Materials Science
Ionic vs covalent character of ceramics determines electrical conductivity and brittleness.
🧪
Analytical Chemistry
Electronegativity differences explain IR stretching frequencies and NMR chemical shifts.

Common Mistakes to Avoid

⚠️
0-0.5 nonpolar, 0.5-1.7 polar, >1.7 ionic

These thresholds are approximate. Chemistry textbooks vary slightly: some use 1.5 or 2.0 as ionic boundary.

⚠️
Pauling scale most common

F=4.0 is reference. Other scales: Mulliken (based on IE and EA), Allen (based on orbital energies). All are correlated.

⚠️
EN difference does not tell full story

Molecular geometry also matters. CO2: two polar bonds but linear geometry gives zero dipole moment.

Frequently Asked Questions

What is electronegativity? ▾
Tendency of an atom to attract electron density toward itself in a bond. Pauling scale: F=3.98 (highest), Fr=0.79 (lowest). Increases across periods, decreases down groups.
What are periodic trends in electronegativity? ▾
Increases across periods (increasing Z_eff). Decreases down groups (increasing atomic radius, farther from nucleus). F is most electronegative; Cs and Fr least.
How does electronegativity affect bond polarity? ▾
dEN determines charge distribution. Large dEN: electrons strongly attracted to more electronegative atom, giving partial charges delta+/delta-.
What is the Hansch-Leo scale? ▾
Hammett sigma constants measure electron-withdrawing/donating effects. Related but different from Pauling electronegativity. Used in physical organic chemistry.
What is the isoelectronic principle? ▾
Atoms with same number of electrons but different Z. Na+ and Ne are isoelectronic. The one with higher Z has stronger nuclear attraction, smaller size, higher IE.

Related Chemistry Calculators

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Formula Explorer connections

Interpretation: This relationship uses electronic structure, bonding or molecular geometry to predict a chemical property or structural descriptor. Assumption: The model may be an approximation; resonance, solvent, coordination environment, conformation and experimental conditions can affect real molecules.

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