Periodic Table and Periodic Trends

Organization of the periodic table and trends in radius, ionization energy, electron affinity, electronegativity, and reactivity.

Intended level

Intermediate — after Atomic Structure & Electron Configuration.

Prerequisites

• atomic-structure
• electron-configuration

Ordered lessons

1. Periodic Table and Periodic Trends: The Complete Guide — FLAGSHIP — 95 min · published 2026-08-22 · 36 sections
2. periodic table organization
3. groups periods blocks
4. metals nonmetals metalloids
5. effective nuclear charge shielding
6. periodic trends overview

Related formulas and calculators

• $effective-nuclear-charge$ — see Formula: effective-nuclear-charge
• periodic-trends

Only links to real, published tools are shown. Placeholders are not linked.

Common misconceptions

• Periodic trends are rules with no exceptions.
• All metals are magnetic.
• Reactivity always increases across a period.

Related resources

• Research Archive — 23 hubs · 286 dossiers — the full knowledge-base pack with searchable dossier browser and download
• Flagship Lesson: Complete Guide — 36 sections, 30+ worked examples
• Interactive Periodic Table — 118 elements with filters, trends, and compare tray
• Constants — sourced physical constants with version stamps.
• Laboratory Safety — PPE, hazards, RAMP.
• Glossary — definitions for key terms in this topic.
• Sources and Data — how sources are versioned and cited.

Curriculum mappings

This topic maps to external frameworks stored in src/content/curriculum/. Never implies official affiliation.

• AP Chemistry 1.1 / IB Chemistry 2.1 (see /curriculum/ap-chem-1-1 and file src/content/curriculum/ap-chem-1-1.md).
• Framework version and source URL recorded per mapping; review date 2026-08-21.

Review and source metadata

• Author: Chemistry Fundamentals Editorial Team (chem-team)
• Reviewer: Dr. Example Reviewer (chemistry reviewer — transparent placeholder, see /editorial-policy)
• Last reviewed: 2026-08-21
• Review due: 2027-08-21
• Sources: NIST Reference Placeholder (nist-2022, 2022-CODATA). Placeholder reference — replace with actual sourced reference per lesson.

Printable summary

Summary card (PDF) — coming soon — print styles preserve equations and tables.

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