The Periodic Grid
Arrangement of Elements · Periods & Groups · Metallic Character
🏙️ The City Map Analogy
Imagine the Periodic Table as a giant city. Periods are horizontal Streets — walk along Street 3 from left to right and the neighbourhood shifts from heavy industrial metals to gaseous, invisible non-metals. Groups are vertical Skyscrapers — every resident in Building 1 (Group I) behaves exactly the same: one outer electron, desperately reactive. The Proton Number is every element's unique postcode: it always wins over mass when deciding where an element lives.
⚠️ Examiner Traps Summary
• Proton number ≠ mass number. Proton number (Z) determines position; mass number depends on neutrons too.
• Group number = outer electrons (for main group elements). Group I = 1 outer electron, Group VII = 7 outer electrons.
• Period number = number of occupied shells. Period 3 elements have 3 shells.
• Metallic character decreases across a period and increases down a group.
Sign In to Keep Going
You've reached the end of the free preview. Sign in — and upgrade to Plus or Pro — to keep going with Chemistry.
Full Access
Unlock all 320 lessons