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Electronegativity Calculator

Chemistry

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

Reviewed by the thecalcu.com team · Last updated July 8, 2025

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.

Why Use an Electronegativity Calculator?

Memorising all Pauling χ values is impractical for less common elements. This calculator stores the complete table for all main-group and common transition metals, so you can look up any pair and instantly get Δχ without consulting a textbook. The bond-type classification (nonpolar/polar covalent/ionic) is also applied automatically, no need to remember where the 0.4 and 1.7 thresholds fall.

For problems comparing multiple bonds (which is most polar: HF, HCl, or H₂O?), you can check each pair in seconds.

Who Should Use This Calculator?

Class 11 students learning chemical bonding (NCERT Chapter 4): electronegativity, bond polarity, and the ionic-covalent continuum are foundational.

JEE Main aspirants ranking bonds by polarity, predicting dipole moments, or explaining periodic trends in electronegativity.

Organic chemistry students assessing C-X bond polarity for nucleophilic substitution (which carbon bears the partial positive charge), or predicting the site of attack in addition reactions.

Inorganic chemists and materials scientists estimating bond ionicity for ceramics, semiconductor alloys, and coordination compounds.

What Insights Does the Electronegativity Calculator Give You?

χ (Element 1) and χ (Element 2) are the Pauling electronegativities, the absolute values tell you how strongly each atom attracts electrons in bonds generally.

Δχ (Difference) is the key quantity for bond polarity: the larger Δχ, the more polar the bond, the greater the partial charges δ+ and δ−.

Bond Character classifies the bond: nonpolar covalent (symmetric sharing, Δχ < 0.4), polar covalent (asymmetric sharing, 0.4–1.7), or predominantly ionic (nearly complete electron transfer, Δχ > 1.7).

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.
Show formula & methodology ↓Show less ↑

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

What is electronegativity and what does it measure?
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+).
How is Pauling electronegativity calculated?
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.
How do I use the Electronegativity Calculator?
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).
What are the electronegativities of the most important elements?
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.
How does electronegativity change across periods and down groups?
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.
What is the difference between Pauling, Mulliken, and Allred-Rochow electronegativity?
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.
What is the electronegativity difference for ionic compound formation?
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.
Why does fluorine have the highest electronegativity?
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).
How does electronegativity determine water's properties?
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).
What is the electronegativity of carbon and why is it important for organic chemistry?
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).