This electronegativity calculator looks up the Pauling electronegativity of any two elements, computes the difference (Δχ) between them, and classifies the bond they would form — nonpolar covalent, polar covalent, or ionic.

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One Number per Element, One Difference per Bond

Electronegativity is an atom's pull on shared electrons, and Linus Pauling's scale — still the working standard — anchors it to fluorine at 3.98 and lets every other element fall where its bond energies put it: oxygen 3.44, chlorine 3.16, nitrogen 3.04, carbon 2.55, hydrogen 2.20, and the metals trailing below 2. The chemistry lives in the DIFFERENCE. Two identical atoms (Δχ = 0) share perfectly; a moderate gap makes one end of the bond electron-rich and the other electron-poor — the origin of molecular polarity, hydrogen bonding, solubility behavior and most of organic reactivity; a gap past ~1.7 means the electron has effectively moved house and you have ions. The defaults show the canonical case: sodium (0.93) against chlorine (3.16) gives Δχ = 2.23 — table salt is ionic because that gap is unbridgeable by sharing.

The periodic pattern is the memory aid that makes the table unnecessary: electronegativity rises across a period (atoms shrink, nuclear pull on the bonding pair strengthens) and falls down a group (the bonding pair sits further out, shielded by more inner shells). That single trend explains why the top-right corner (F, O, Cl, N) hoards electrons and the bottom-left (Cs, Fr, K) surrenders them — and why carbon and hydrogen, near-neighbors at 2.55 and 2.20, form the near-nonpolar scaffolding of organic molecules, while C–O and O–H bonds carry the polarity that makes biochemistry possible in water.

Worked Examples (Verified)

  • Sodium + Chlorine: Δχ = 3.16 − 0.93 = 2.23 → ionic (NaCl).
  • Hydrogen + Fluorine: Δχ = 3.98 − 2.20 = 1.78 — past the ionic line by the number, polar covalent in behavior (the famous exception).
  • Carbon + Oxygen: Δχ = 3.44 − 2.55 = 0.89 → polar covalent (the C=O polarity behind CO₂'s reactivity).
  • Carbon + Hydrogen: Δχ = 2.55 − 2.20 = 0.35 → nonpolar covalent (why hydrocarbons shun water).

Electronegativity Discipline

  • Pauling is the default scale; Mulliken and Allred–Rochow scales rank elements almost identically but quote different numbers — never mix scales inside one comparison.
  • Δχ classifies the BOND, not the substance: NaCl is ionic in the crystal, but AlCl₃ (Δχ 1.55) sublimes as molecules — structure always gets the last word.
  • The 1.7 boundary is a convention, not a law of nature; bonds between 1.5 and 2.0 are honestly described as "highly polar / partially ionic," which the percent-ionic-character formula quantifies.
  • Noble gases mostly lack Pauling values (they declined to bond for the measurements) — their absence from the table is data, not an oversight.
  • Oxidation-state electronegativity varies slightly (Fe³⁺ pulls harder than Fe²⁺); the table values are the standard neutral-atom figures used for classification.

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Frequently Asked Questions

What is electronegativity?

Electronegativity is an element's tendency to attract shared electrons in a chemical bond, measured on the Pauling scale from ~0.8 (cesium, francium) to 3.98 (fluorine). It rises across the periodic table and falls down it. This calculator gives the Pauling values for two elements and their difference, which predicts bond polarity: under 0.4 nonpolar covalent, 0.4–1.7 polar covalent, 1.7+ ionic.

Which element has the highest electronegativity?

Fluorine, at 3.98 on the Pauling scale — the anchor of the whole system. Oxygen (3.44) is second and chlorine (3.16) third, which is why bonds to F and O dominate polarity discussions: any element paired with fluorine faces the largest possible Δχ, and oxides carry strong partial charges. At the other end, cesium and francium (~0.7–0.8) hold their electrons most loosely — the most electropositive elements form the most completely ionic compounds.

How does electronegativity difference determine bond type?

Subtract the two Pauling values and read the band: Δχ < 0.4 → electrons shared nearly equally, nonpolar covalent (C–H at 0.35, H–H at 0). Δχ 0.4–1.7 → unequal sharing, polar covalent, with δ− on the more electronegative atom (H–Cl at 0.96). Δχ ≥ 1.7 → effective electron transfer, ionic (Na–Cl at 2.23). The bands are conventions over a continuum — the calculator reports the band, and borderline pairs (HF, 1.78) deserve the "highly polar" conversation rather than a label fight.

Why is HF considered polar covalent if its Δχ is 1.78?

Because classification by number alone misses structure: HF exists as discrete molecules with a shared (if very lopsided) electron pair, hydrogen fluoride gas doesn't conduct, and there's no lattice of H+ and F− ions — a bare proton is far too small and polarizing to live as a free ion in a crystal. The Δχ rule works because most pairs past 1.7 involve a metal that forms a stable cation; hydrogen is the standing exception, and it's why the threshold is taught as approximate.

What is the electronegativity of oxygen and carbon?

Oxygen is 3.44 and carbon is 2.55 on the Pauling scale, a difference of 0.89 — firmly polar covalent. That single gap explains a lot of the observable world: carbonyl bonds (C=O) are reactive at both ends, CO₂'s oxygens carry partial negative charge, and carbon's mid-scale position (with hydrogen just below at 2.20) is exactly what lets carbon build near-nonpolar skeletons decorated with polar functional groups — the architecture of organic chemistry.

Does electronegativity predict solubility?

Indirectly but usefully: bonds with large Δχ make molecules polar, and polar molecules dissolve in polar solvents ("like dissolves like") while nonpolar ones don't — which is why salt (ionic) and sugar (polar O–H bonds) dissolve in water while oils (C–H, Δχ 0.35) refuse. The prediction runs through the molecule's overall dipole, not any single bond: CO₂ has polar bonds but a nonpolar molecule (the two pulls cancel by symmetry), and it behaves accordingly.

Electronegativity vs electron affinity — what's the difference?

Electron affinity is a measured energy: how much energy an isolated gas-phase atom releases when it gains an electron. Electronegativity is a constructed scale describing an atom's pull on electrons it is already SHARING in a bond. They're cousins (both track the F/O/Cl corner) but not interchangeable: chlorine has the highest electron affinity, fluorine the highest electronegativity. Exam questions swap them maliciously; the distinction is "gaining alone" vs "pulling while sharing."

Is this electronegativity calculator free?

Yes — free, instant, no sign-up. Pick any two elements for their Pauling values, the difference, and the bond classification.