SubjectNest resource library

Development draft · local review needed

Day 4 · Isotopes share identity, not neutronsYear 11 Chemistry · T1 W1–2 · Day 4 lesson

Prepare this lesson

Year 11 / Chemistry / Term 1 / Weeks 01 02

Part of the full two-week lesson sequence. Check the pack guide and taught point before teaching.

Open for this lesson: Pack guide · Daily routes · Worked swaps · Fresh learner checks · Aids and text routes.

Download full sequence

Teacher copy: This page may include teaching prompts or answer keys. Answer keys in this public library can be viewed by anyone. Give learners a clean prompt, use checks as formative evidence, and change a case locally when prior access matters.

Learner prompts

Target: compare neutral carbon-12/carbon-13 and chlorine-35/chlorine-37 by Z, A and neutron count. Prepare: Cards D/E and isotope/ion fork; give chlorine Z 17.

  1. Launch · 2 min. Ask whether carbon-13 must have more protons than carbon-12 because “13 is larger.”
  2. Model · 4 min. Same carbon Z 6 means six protons. Carbon-12 has 6 neutrons; carbon-13 has 7. Isotope difference is nuclear neutron count.
  3. Guided reading · 5 min. Contrast chlorine-35/37: both Z 17, neutrons 18/20. These are isotope names, not evidence of their natural abundance or chemical safety.
  4. Practice route · 7 min. Choose Day 4 route; compare both pairs using a shared-Z statement, two neutron calculations and a bounded conclusion.
  5. Audit · 4 min. Peer calls carbon-12 and magnesium-24 isotopes because both are “atoms”; learner repairs by testing Z.
  6. Exit · 3 min. “Which count differs within an isotope pair?” Key: neutron count (and A), while proton count/Z stays the same.

Source: https://neuroforge.io/subjectnest/library/resources/year-11/chemistry/term-1/weeks-01-02/day-04 · Original material © NeuroForgeIO Pty Ltd 2026 · CC BY 4.0: https://creativecommons.org/licenses/by/4.0/ · Credit the source and note changes. External sources keep their own terms.