Electronegativity Calculator

About the Electronegativity Calculator

Electronegativity measures an atom's ability to attract bonding electrons toward itself. It is one of the most important periodic properties in chemistry, governing bond polarity, molecular shape, reactivity, and intermolecular forces. The Pauling scale (0.7 to 4.0) is the most widely used, but the Mulliken and Allred-Rochow scales offer complementary perspectives.

The electronegativity difference (ΔEN) between two bonded atoms predicts the bond type: ΔEN < 0.5 is nonpolar covalent, 0.5–1.7 is polar covalent, and > 1.7 is predominantly ionic. This simple rule lets you quickly assess any bond just by looking up two numbers on the periodic table.

This calculator compares electronegativity values for any two elements, predicts bond type and percent ionic character, shows periodic trends, and provides a reference table with Pauling values for common elements. It also converts between the Pauling, Mulliken, and Allred-Rochow scales.

When This Page Helps

Quickly predict bond polarity and type from any pair of elements. Compare electronegativity scales and understand periodic trends. Essential for general and organic chemistry.

How to Use the Inputs

1. Select two elements to compare their electronegativity values.
2. View the ΔEN and predicted bond type (nonpolar, polar covalent, or ionic).
3. Check the estimated percent ionic character using Pauling's formula.
4. Explore periodic trends with the trend visualization.
5. Switch between Pauling, Mulliken, and Allred-Rochow scales.
6. Click preset bond pairs for common examples.
7. Review the full reference table for all elements.

Example Calculation

Tips & Best Practices

• Electronegativity increases left-to-right across a period and bottom-to-top in a group.
• Fluorine (3.98) > Oxygen (3.44) > Nitrogen (3.04) > Chlorine (3.16) are the most electronegative elements.
• Metals generally have EN < 2.0; nonmetals have EN > 2.5. Metalloids fall in between.
• Equal electronegativity between bonded atoms = perfectly nonpolar covalent (e.g., H-H, Cl-Cl).
• Bond polarity determines solubility rules: "like dissolves like" depends on molecular polarity from EN differences.
• Mulliken scale uses ionization energy and electron affinity — both measurable quantities.

Pauling vs. Mulliken vs. Allred-Rochow

Linus Pauling's scale (1932) derives electronegativity from bond dissociation energies. Robert Mulliken's scale (1934) uses the average of ionization energy and electron affinity. The Allred-Rochow scale (1958) estimates the electrostatic force exerted by the effective nuclear charge on bonding electrons. All three correlate well but differ in numerical values.

Electronegativity and Organic Chemistry

In organic chemistry, electronegativity differences determine functional group reactivity. Carbonyl groups (C=O) are reactive because oxygen pulls electron density away from carbon. Electronegativity also explains why fluorine substitution changes drug properties, why amines are basic, and why carbon-fluorine bonds are among the strongest single bonds known.

Beyond Atomic Electronegativity

Group electronegativity assigns EN values to functional groups (e.g., -CF₃ is more electronegative than -CH₃). Electronegativity equalization models predict charge distribution in molecules. Allen's spectroscopic electronegativity uses average orbital energies for a more rigorous definition.

Frequently Asked Questions

• What is the most electronegative element?

  Fluorine, with a Pauling electronegativity of 3.98 — the highest of any element. It attracts bonding electrons more strongly than any other atom.

• What is the least electronegative element?

  Francium or cesium at ~0.7 on the Pauling scale. Low electronegativity elements easily lose electrons and form cations.

• Is the 1.7 cutoff for ionic bonds exact?

  No — it's an approximation. Many bonds near ΔEN = 1.7 show mixed character. Percent ionic character provides a more nuanced picture. Even NaCl has only ~76% ionic character.

• Why don't noble gases have electronegativity values?

  Noble gases rarely form bonds, so electronegativity is typically not defined for them. Some scales assign values for Xe and Kr based on their known compounds.

• How does electronegativity relate to polarity?

  The more electronegative atom in a bond carries a partial negative charge (δ-), the less electronegative gets δ+. This creates a bond dipole that contributes to molecular polarity.

• Why does electronegativity increase across a period?

  As you move right across a period, nuclear charge increases while shielding stays roughly constant, so the effective nuclear charge on bonding electrons increases — atoms pull harder on shared electrons. This keeps planning practical and lowers the chance of preventable errors.