Electronegativity

Science

Definition

Electronegativity is a measure of an atom's ability to attract shared electrons in a chemical bond. It increases across a period (left to right) and decreases down a group on the periodic table. Differences in electronegativity determine bond type.

Examples

  • Fluorine has the highest electronegativity (3.98) of any element, making it extremely reactive
  • The large electronegativity difference between Na and Cl creates an ionic bond in NaCl
  • Water is polar because oxygen (3.44) is much more electronegative than hydrogen (2.20)
Key Fact

EN difference: 0-0.4 = nonpolar covalent; 0.4-1.7 = polar covalent; >1.7 = ionic (approximate guidelines).

Related Terms

Periodic trends Covalent bonds Ionic bonds Dipole-dipole

Study This Concept

Practice electronegativity with free review games in these units:

Chemistry Unit 3: Chemical Bonding