About the Bond Polarity Calculator
This bond polarity calculator looks up the Pauling electronegativity of two elements, finds the difference (ΔEN) and classifies the bond between them as nonpolar covalent, polar covalent or ionic. It also tells you which atom carries the partial negative charge (δ−) and estimates the percent ionic character with Pauling’s formula.
Type element symbols (O, Cl, Na) or names (oxygen, chlorine). Electronegativities for 95 elements come from the PubChem Periodic Table, and the cut-offs follow OpenStax Chemistry 2e: below 0.4 is nonpolar (pure) covalent, 0.4 to 1.8 is polar covalent, and above 1.8 is ionic. Some textbooks put the ionic boundary at 1.7 or 2.0, so check which convention your course uses.
Electronegativity difference is only a rough guide. HF has ΔEN = 1.78 on the Pauling scale used here (about 1.9 on some other tables), right at the ionic boundary, yet it is a covalent molecule, while some metal–nonmetal pairs with smaller differences still form ionic solids. Bonds between two nonmetals are usually covalent; bonds between a metal and a nonmetal are often ionic.
With the default inputs, the electronegativity difference δen is 0.96. Change any value above to recalculate instantly.
How to use the bond polarity calculator
- 1Enter the first element as a symbol or name.
- 2Enter the second element.
- 3Read the electronegativity difference and the bond type.
- 4Check which atom is δ− and the estimated percent ionic character.
Formula and method
Electronegativity (χ) measures how strongly an atom attracts the shared electrons in a bond. The calculator takes the absolute difference between the Pauling electronegativities of the two atoms, rounds it to two decimals and classifies the bond: ΔEN below 0.4 is treated as nonpolar covalent, 0.4 to 1.8 as polar covalent, and above 1.8 as ionic, following OpenStax Chemistry 2e Figure 7.8.
The percent ionic character uses Linus Pauling’s empirical relationship, which rises smoothly from 0% for identical atoms to about 55% at ΔEN = 1.8 and over 85% at ΔEN = 2.8. The more electronegative atom gets the partial negative charge δ−.
- χA, χB
- Pauling electronegativity of atoms A and B
- ΔEN
- Absolute electronegativity difference
Worked examples
Hydrogen chloride (H–Cl)
H has χ = 2.20 and Cl has χ = 3.16. The difference of 0.96 falls between 0.4 and 1.8, so H–Cl is polar covalent with chlorine carrying the partial negative charge, about 21% ionic character.
Sodium chloride (Na–Cl)
Sodium (0.93) and chlorine (3.16) differ by 2.23, well above 1.8, so the bond is ionic: sodium gives up its electron to form Na⁺ and Cl⁻.
Carbon–hydrogen bond
C (2.55) and H (2.20) differ by only 0.35, below the 0.4 cut-off, which is why C–H bonds are treated as essentially nonpolar and hydrocarbons do not mix with water.
Frequently asked questions
How do you determine if a bond is polar or nonpolar?+
Subtract the electronegativities of the two atoms. A difference below about 0.4 means electrons are shared nearly equally (nonpolar); 0.4 to 1.8 means unequal sharing (polar covalent); larger differences indicate an ionic bond.
Is the cut-off for ionic bonds 1.7 or 1.8?+
Both are used. OpenStax and many US texts use 1.8, others use 1.7 (where Pauling’s formula gives about 50% ionic character) or 2.0. The boundary is a convention, not a sharp physical change.
Which atom gets the partial negative charge?+
The more electronegative atom pulls the shared electrons toward itself and gets δ−. In H–O, oxygen (3.44) is δ− and hydrogen (2.20) is δ+.
Can a molecule with polar bonds be nonpolar?+
Yes. If polar bonds are arranged symmetrically their dipoles cancel, as in CO₂ (linear) or CCl₄ (tetrahedral). Molecular polarity depends on both bond polarity and shape.
Where do the electronegativity values come from?+
They are Pauling-scale values published in the PubChem Periodic Table from the US National Library of Medicine. Fluorine is the most electronegative element at 3.98.