Electronegativity Difference — how far do the electrons go?
Pick two elements. The bigger the gap in electronegativity, the further the shared electrons
drift toward the stronger atom — until, at the far end, they stop being shared at all. The
difference is a number, and the number tells you which kind of bond you have.
Dashed border = metal. Electronegativity values are the one-decimal table used in class.
The difference
Nonpolar covalent 0.0 – 0.4
Polar covalent 0.5 – 1.8
Ionic 1.9 – 3.3
electrons shared equally
electrons shared unequally
electrons transferred
What the electrons do
The class analogy: a crowd on a street drifts toward the more famous person. The cloud is a
picture of where the electrons spend their time — there are no percentages on it.
Bonds worked in class
δ⁻ and δ⁺ are partial charges — the electrons leaned over but stayed shared. Full
+ and − mean they left. That is the whole difference between polar covalent and ionic.