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Electronegativity Calculator

Chemistry

Look up Pauling electronegativity for any element (Z=1–86) and calculate the electronegativity difference between two bonded atoms. Includes bond polarity classification.

χ (Element 1)

3.44
χ (Element 2)
2.2
Δχ (Difference)
1.24
Bond Character
Polar covalent (0.4 ≤ Δχ < 1.7)

This calculator computes your χ (Element 1), χ (Element 2), Δχ (Difference), Bond Character from the values you enter.

Inputs
Element 1 (Atomic Number)Element 2 (Atomic Number)
Outputs
χ (Element 1)χ (Element 2)Δχ (Difference)Bond Character

What is a Electronegativity?

The Electronegativity Calculator looks up the Pauling electronegativity (χ) for two elements and computes their difference Δχ = |χ₁ − χ₂|, classifying the bond as nonpolar covalent, polar covalent, or predominantly ionic. Select elements from the dropdown — each entry shows the Pauling χ value — to instantly assess bond polarity.

Electronegativity is the atomic property that determines how electron density is distributed in a chemical bond. When two atoms form a bond, the more electronegative one attracts the shared electrons more strongly, acquiring a partial negative charge (δ−). This charge separation is the origin of bond polarity, molecular dipole moments, hydrogen bonding, solubility, and reactivity in organic mechanisms. Every polarity prediction in chemistry starts with electronegativity.

The O-H bond (default: χ_O=3.44, χ_H=2.20, Δχ=1.24, polar covalent) is the most important bond in biology — water's polarity from O-H bonds drives hydrogen bonding, hydration shells, and protein folding. The Percent Ionic Character Calculator converts Δχ to a quantitative percentage (33% ionic for O-H). The Effective Nuclear Charge Calculator explains why electronegativities follow periodic trends.

How to use this Electronegativity calculator

  1. Select Element 1 from the dropdown — elements shown with Z, symbol, and χ value.
  2. Select Element 2 from the dropdown — the second atom in the bond.
  3. Read χ (Element 1) and χ (Element 2) — the individual Pauling electronegativities.
  4. Read Δχ — use this to estimate bond polarity and relate to the Percent Ionic Character Calculator.
  5. Read Bond Character for the qualitative classification.

Formula & Methodology

Electronegativity difference:

Δχ = |χ₁ − χ₂|  Bond type thresholds (Pauling): Δχ < 0.4:   Nonpolar covalent 0.4–1.7:    Polar covalent Δχ > 1.7:   Predominantly ionic

Worked example — comparing period 3 element bonds with hydrogen:

H: χ = 2.20

Na-H: Δχ = |0.93 − 2.20| = 1.27  → Polar covalent (hydrides: H is δ−, Na is δ+) Mg-H: Δχ = |1.31 − 2.20| = 0.89  → Polar covalent Al-H: Δχ = |1.61 − 2.20| = 0.59  → Polar covalent Si-H: Δχ = |1.90 − 2.20| = 0.30  → Nonpolar covalent P-H:  Δχ = |2.19 − 2.20| = 0.01  → Nonpolar covalent (phosphine PH₃) S-H:  Δχ = |2.58 − 2.20| = 0.38  → Nonpolar covalent (borderline) Cl-H: Δχ = |3.16 − 2.20| = 0.96  → Polar covalent (HCl: H is δ+, Cl is δ−)

Notice that Na-H reverses polarity vs Cl-H: in NaH, hydrogen is the more electronegative atom (δ−), making NaH a hydride (H⁻). In HCl, hydrogen is less electronegative (δ+). This polarity reversal — from Na-H to Si-H to Cl-H — marks the transition from saline hydrides (ionic, reactive with water) to covalent hydrides (molecular, acidic). This is a standard JEE Advanced classification topic.

Frequently Asked Questions

Electronegativity (χ) is a measure of an atom's tendency to attract the shared electron pair in a chemical bond toward itself. It is a dimensionless property of an atom in a molecule — not a property of the free atom in isolation. The most widely used scale is the Pauling scale, ranging from 0.7 (Cs, most electropositive) to 3.98 (F, most electronegative). A high electronegativity means the atom pulls bonding electrons strongly toward itself, creating partial negative charge (δ−). A low electronegativity means the atom donates electron density, becoming partially positive (δ+).
Linus Pauling (1932) derived electronegativity from thermochemical data. He observed that the A-B bond dissociation energy is always greater than the geometric mean of the A-A and B-B bond energies: D(A-B) > √(D(A-A) × D(B-B)). The extra stabilisation (Δ = D(A-B) − √(D(A-A)×D(B-B))) comes from the ionic contribution to the bond. Pauling showed Δ ∝ (χ_A − χ_B)²: χ_A − χ_B = 0.102 × √Δ (with Δ in kJ/mol). Fluorine (χ=3.98) was assigned the highest value; the scale is internally consistent but anchored to this reference.
Select Element 1 and Element 2 from the dropdowns (listed with atomic number, symbol, and Pauling χ value). The calculator returns χ for each element and Δχ = |χ₁ − χ₂|, then classifies the bond: nonpolar covalent (Δχ < 0.4), polar covalent (0.4–1.7), or predominantly ionic (Δχ > 1.7). Default: O-H bond (O: χ=3.44, H: χ=2.20, Δχ=1.24, polar covalent).
F = 3.98 (most electronegative element). O = 3.44. N = 3.04. Cl = 3.16. Br = 2.96. S = 2.58. C = 2.55. H = 2.20. P = 2.19. I = 2.66. Fe = 1.83. Al = 1.61. Mg = 1.31. Ca = 1.00. Na = 0.93. K = 0.82. Noble gases (He, Ne, Ar) have no Pauling electronegativity because they don't form covalent bonds with stable dissociation energy data. The mnemonic for the most electronegative elements: F > O > N ≈ Cl > Br > I > S > C > H.
Across a period (left to right): electronegativity increases because Z increases while shielding changes little — the [Effective Nuclear Charge Calculator](/effective-nuclear-charge-calculator/) shows Z* increases, pulling bonding electrons more strongly. Example (Period 3): Na=0.93, Mg=1.31, Al=1.61, Si=1.90, P=2.19, S=2.58, Cl=3.16. Down a group: electronegativity decreases because atomic radius increases (bonding electrons are farther from the nucleus) and inner-shell shielding increases. Example (Group 17): F=3.98, Cl=3.16, Br=2.96, I=2.66.
Pauling electronegativity: based on bond dissociation energies; ranges 0.7–4.0; most widely used in chemistry. Mulliken electronegativity (χ_M): average of ionisation energy (IE) and electron affinity (EA): χ_M = (IE + EA)/2, in eV; converts to Pauling scale approximately via χ_P ≈ 0.336 × (χ_M − 0.615). Allred-Rochow electronegativity: based on the electrostatic force at the covalent radius: χ_AR = 0.359 × Z*/r² + 0.744. All three give consistent trends but different absolute values. NCERT and JEE use the Pauling scale; research papers may use any of the three.
The traditional rule: Δχ > 1.7 gives > 50% ionic character (Hanney-Smith formula). Compounds like NaF (Δχ = 3.05), NaCl (Δχ = 2.23), KBr (Δχ = 2.14), MgO (Δχ = 2.13) are predominantly ionic. However, there is no sharp cutoff — the [Percent Ionic Character Calculator](/percent-ionic-character-calculator/) gives the continuous percentage: NaCl at Δχ=2.23 has ~70% ionic character. Even NaF (~80% ionic) retains some covalent character. Conversely, all covalent bonds with Δχ > 0 have some ionic character. The ionic/covalent classification is a model, not a strict boundary.
Fluorine (F, Z=9) has the highest electronegativity (3.98) for two reasons: (1) High effective nuclear charge: F's 2p valence electrons experience Z* ≈ 5.2 (calculated using Slater's rules with small n=2 shell shielding) — strong nuclear pull on bonding electrons. (2) Small atomic radius (64 pm): the bonding electrons are very close to the nucleus, experiencing a strong attraction. Despite having lower Z than Cl, F's smaller size gives it higher electronegativity than Cl (3.16). This makes F the strongest oxidising agent — it can oxidise almost any element and even some noble gases (XeF₂, XeF₄).
Water (H₂O): O has χ=3.44, H has χ=2.20, Δχ=1.24 → polar covalent bonds. The O pulls bonding electrons strongly, creating δ−O and δ+H partial charges. This polarity gives water: a dipole moment of 1.85 D, the ability to form hydrogen bonds (responsible for high boiling point 100°C vs −61°C for H₂S), and the ability to dissolve ionic compounds (like NaCl) and polar covalent molecules (like glucose and ethanol). These properties make water the universal solvent — critical for all biological processes and industrial chemistry in India (water scarcity and quality are major national concerns).
Carbon's electronegativity is 2.55 — essentially in the middle of the Pauling scale. C-H bonds have Δχ=0.35 (nearly nonpolar); C-O bonds have Δχ=0.89 (polar, O is δ−); C-F bonds have Δχ=1.43 (strongly polar, F is δ−); C-Li bonds have Δχ=1.57 (highly polar, Li is δ+). Carbon's moderate electronegativity means C-H bonds are only weakly polar (explaining why hydrocarbons like petroleum are non-polar solvents, immiscible with water — a key property for India's petroleum refining industry at IOC Panipat, BPCL Mumbai). C-X bond polarity determines reactivity in organic mechanisms (nucleophilic substitution, addition, elimination).