Atomic Structure

Protons, neutrons, electrons, isotopes, ions, and how subatomic structure determines identity and behavior.

Intended level

Beginner — after Foundations and Matter & Measurement.

Prerequisites

• chemistry-foundations
• matter-measurement

Ordered lessons

1. atomic models
2. protons neutrons electrons
3. atomic mass number
4. isotopes
5. average atomic mass
6. ions
7. electromagnetic spectrum photons
8. bohr model limitations
9. orbitals quantum numbers

Related formulas and calculators

• $average-atomic-mass$ — see Formula: average-atomic-mass
• $photon-energy$ — see Formula: photon-energy
• molar-mass
• isotopic-mass

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

Common misconceptions

• Electrons orbit like planets.
• Atoms are solid spheres.
• Isotopes are different elements.

Related resources

• 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.

Correction? See Corrections Policy and Contact.