Periodic Trends Visualizer
Pick a trend below and watch it paint the table: warmer colours mean higher values. Each trend comes with its one-line rule for periods and groups, and the reason behind it.
Across a period →
Decreases → across a period
Down a group ↓
Increases ↓ down a group
Why?
Across a period, extra protons pull the same shells inward. Down a group, whole new shells are added.
Warmer colours = higher atomic radius. Learn more in the periodic trends study guide.
Tip: scroll the table sideways, or switch views.
The one picture worth memorising
Almost every trend question resolves to one mental image: fluorine's corner (top right) means small atoms, high ionization energy and high electronegativity; francium's corner (bottom left) means the opposite — large atoms that shed electrons readily, making them the most metallic. Rank any set of elements by asking which sits closer to which corner.
Practice
Try ranking these before checking with the visualizer: (1) Na, K, Rb by atomic radius; (2) C, N, O by electronegativity; (3) Mg, Al, Si by ionization energy. Then test yourself properly in the Periodic Trends Quiz or read the full Periodic Trends study guide.
Frequently asked questions
What are the four main periodic trends?
Atomic radius (decreases across, increases down), ionization energy (increases across, decreases down), electronegativity (same directions as ionization energy) and metallic character (opposite — decreases across, increases down).
Why do periodic trends exist?
Two competing effects: crossing a period adds protons that pull on the same shells (stronger grip, smaller atoms), while going down a group adds whole shells that push outer electrons farther out and shield them (weaker grip, bigger atoms).
Which element is the most electronegative?
Fluorine, at about 4.0 on the Pauling scale. Electronegativity falls as you move away from fluorine's corner of the table.
Are there exceptions to periodic trends?
Small local dips exist (for example ionization energy between groups 2→13 and 15→16), but the overall directions hold well enough to answer ranking questions reliably.