Electronegativity Calculator
Free Electronegativity Calculator for general chemistry. Enter variables to compute results with formulas and detailed steps.
Reviewed by Manoj Kumar, Mathematics Educator
Formula
Bond Type: |EN1 - EN2| < 0.4 = Nonpolar; 0.4-1.7 = Polar Covalent; > 1.7 = Ionic
Electronegativity measures how strongly an atom attracts bonding electrons. The difference between two atoms determines bond polarity. Percent ionic character is estimated using the formula: % ionic = (1 - e^(-0.25 x delta^2)) x 100.
Worked Examples
Example 1: Bond Type of HCl
Problem:Determine the bond type between hydrogen (EN = 2.20) and chlorine (EN = 3.16).
Solution:Difference = |2.20 - 3.16| = 0.96\n0.4 < 0.96 < 1.7, so Polar Covalent\nPercent ionic = (1 - e^(-0.25 x 0.96^2)) x 100 = 20.8%\nChlorine is more electronegative and has partial negative charge.
Result:Polar Covalent (delta = 0.96)
Example 2: Bond Type of NaCl
Problem:Classify the bond between sodium (EN = 0.93) and chlorine (EN = 3.16).
Solution:Difference = |0.93 - 3.16| = 2.23\n2.23 >= 1.7, so Ionic\nPercent ionic = (1 - e^(-0.25 x 2.23^2)) x 100 = 71.8%\nElectrons are essentially transferred from Na to Cl.
Result:Ionic (delta = 2.23)
Frequently Asked Questions
What is electronegativity and how is it measured?
Electronegativity is a measure of how strongly an atom attracts shared electrons in a chemical bond. The most commonly used scale is the Pauling scale, developed by Linus Pauling, which ranges from about 0.7 (francium) to 3.98 (fluorine). Electronegativity generally increases from left to right across a period and decreases from top to bottom within a group on the periodic table. Noble gases are typically not assigned electronegativity values since they rarely form bonds.
How does electronegativity difference determine bond type?
The difference in electronegativity between two bonded atoms determines the bond polarity. If the difference is less than 0.4, the bond is considered nonpolar covalent, meaning electrons are shared roughly equally. A difference between 0.4 and 1.7 indicates a polar covalent bond, where electrons are unequally shared. A difference of 1.7 or greater typically results in an ionic bond, where electrons are essentially transferred from the less electronegative atom to the more electronegative one.
Why does fluorine have the highest electronegativity?
Fluorine has the highest electronegativity (3.98 on the Pauling scale) because of its small atomic radius and high effective nuclear charge. With only 7 electrons in its valence shell and needing just one more to complete its octet, fluorine atoms exert an extremely strong pull on bonding electrons. Its small size means the nucleus is close to the bonding electrons, increasing the attractive force. This makes fluorine the most reactive nonmetal and explains why it forms very strong bonds with most other elements.
What is the relationship between electronegativity and percent ionic character?
Percent ionic character can be estimated from the electronegativity difference using the equation: % ionic = (1 - e^(-0.25 x delta^2)) x 100, where delta is the electronegativity difference. A perfectly covalent bond (delta = 0) has 0% ionic character, while large differences approach 100% ionic character. Even ionic bonds are not 100% ionic in practice. For example, NaCl with a delta of 2.23 has about 74% ionic character, indicating some covalent contribution even in this classic ionic compound.
References
Reviewed by Manoj Kumar, Mathematics Educator · Editorial policy