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Day 7 · A positive ion has fewer electronsYear 11 Chemistry · T1 W1–2 · Day 7 lesson

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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.

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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: keep the nucleus fixed while finding electron counts for sodium-23 1+ and magnesium-24 2+. Prepare: Cards B/C/D, count mat and isotope/ion fork.

  1. Launch · 2 min. Place two paper cards “neutral sodium-23” and “sodium-23 1+.” Ask what changed if the isotope name stayed fixed.
  2. Model · 4 min. Sodium Z 11: neutral e 11; 1+ has e 10. Protons remain 11, neutrons 23 − 11 = 12. One electron lost produces net positive charge.
  3. Guided reading · 5 min. Magnesium-24 Z 12: neutral e 12; 2+ has e 10, while p/n remain 12/12. Do not teach a mechanism for a real reaction from this count alone.
  4. Practice route · 7 min. Choose Day 7 route; compare both neutral-to-ion pairs and state what stayed fixed.
  5. Audit · 4 min. Peer subtracts one proton to make 1+. Learner corrects: electron loss changes charge, proton loss changes element.
  6. Exit · 3 min. “Magnesium-24 2+: electrons?” Key: 10, with 12 protons and 12 neutrons.

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