A dimensionless measure of how strongly an atom attracts the shared electrons in a covalent bond toward itself, quantified on the Pauling scale from 0. Electronegativity explains why water is polar and can dissolve salts, why oil and water do not mix, and why certain bonds break more easily than others.
Definition
A dimensionless measure of how strongly an atom attracts the shared electrons in a covalent bond toward itself, quantified on the Pauling scale from 0.7.
💡 Intuition
How 'greedy' an atom is for electrons. Fluorine is most greedy.
🎯 Core Idea
Electronegativity differences between bonded atoms determine whether a bond is polar or nonpolar.
Example
Notation
\chi (chi) denotes electronegativity on the Pauling scale. \delta^+ and \delta^- indicate partial charges from unequal electron sharing. EN values are dimensionless numbers.
🌟 Why It Matters
Electronegativity explains why water is polar and can dissolve salts, why oil and water do not mix, and why certain bonds break more easily than others. It is the key concept linking atomic properties to molecular behavior.
💭 Hint When Stuck
When using electronegativity, compare values between bonded atoms. First look up each atom's Pauling electronegativity value. Then calculate the difference: > 1.7 suggests ionic, 0.4-1.7 suggests polar covalent, < 0.4 suggests nonpolar covalent. Finally, remember the trend: electronegativity increases going right and up on the periodic table.
Formal View
Related Concepts
🚧 Common Stuck Point
Large difference → ionic bond. Small difference → nonpolar covalent. Medium → polar covalent.
⚠️ Common Mistakes
- Confusing electronegativity with electron affinity — electronegativity measures attraction in a bond, electron affinity measures energy released when a free atom gains an electron
- Thinking noble gases have high electronegativity — noble gases generally do not form bonds, so electronegativity is not typically assigned
- Forgetting the periodic trend — electronegativity increases toward the top-right of the periodic table, with fluorine being the most electronegative element
Frequently Asked Questions
What is Electronegativity in Chemistry?
A dimensionless measure of how strongly an atom attracts the shared electrons in a covalent bond toward itself, quantified on the Pauling scale from 0.7.
When do you use Electronegativity?
When using electronegativity, compare values between bonded atoms. First look up each atom's Pauling electronegativity value. Then calculate the difference: > 1.7 suggests ionic, 0.4-1.7 suggests polar covalent, < 0.4 suggests nonpolar covalent. Finally, remember the trend: electronegativity increases going right and up on the periodic table.
What do students usually get wrong about Electronegativity?
Large difference → ionic bond. Small difference → nonpolar covalent. Medium → polar covalent.
Prerequisites
Next Steps
How Electronegativity Connects to Other Ideas
To understand electronegativity, you should first be comfortable with covalent bond. Once you have a solid grasp of electronegativity, you can move on to polar covalent and polarity.
Visualization
StaticVisual representation of Electronegativity