Periodic trends: size, energy, and affinity

What you’ll practice

Periodic trends can feel simple until you hit real comparisons, exceptions, and charged species. This quiz focuses on the patterns behind atomic radius, ionization energy, electron affinity, and electronegativity across the periodic table.

Each question uses 4 options and there’s no timer, so you can slow down to reason through shielding, effective nuclear charge, and subshell effects.

Common pitfalls to avoid

Many mistakes come from mixing up “across a period” vs “down a group,” or forgetting that ions change size dramatically compared with their neutral atoms. Another frequent trap is assuming every trend is perfectly smooth without accounting for subshell stability and electron pairing.

How difficulty and length are balanced

Difficulty is mixed: you’ll see straightforward trend direction questions alongside tougher comparisons and exception-based items. Before starting, choose how many questions you want to answer and pick an easier or harder setting to match your current comfort level.

Quick tips for better accuracy

• Remember: atomic radius generally decreases across a period and increases down a group
• For ionization energy, watch for common “dips” tied to subshell starts and electron pairing
• Electron affinity trends are strong but not perfectly uniform; know the notable exceptions
• Compare ions by charge and electron count first, then apply size logic
• When stuck, think in terms of effective nuclear charge vs shielding rather than memorizing arrows