Guides
What Is Electronegativity? Periodic Trends Explained
Electronegativity measures how strongly an atom attracts the shared electrons in a bond, usually on the Pauling scale — the higher the value, the more it pulls electrons.
Definition & scale
On the Pauling scale, fluorine is highest (3.98), followed by oxygen, nitrogen and chlorine; the alkali metals are lowest (caesium, francium ≈ 0.7).
Periodic trends
- Across a period (left → right): increases. Higher nuclear charge and smaller radius pull electrons more strongly.
- Down a group (top → bottom): decreases. More shells, larger radius and more shielding weaken the pull.
So electronegativity is highest at the top-right (F, O) and lowest at the bottom-left (Cs, Fr).
Why it matters
- Predicts bond type: a large difference → more ionic, small → covalent, equal → non-polar covalent.
- Indicates molecular and bond polarity.
- Reflects metallic vs non-metallic character.
See it visually in the data visualizations (electronegativity heatmap/trend); per-element values are on each element page.