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Science lesson plan · 9th grade (Year 10 in England) · 60 minutes

Identify metal ions with flame tests and precipitates

Chemical reactions, acids and bases

CCSS NGSS.HS-PS1-2CCSS NGSS.SEP 3England: GCSE Chemistry: Chemical analysis (identification of ions)

Objective and success criteria

Students will: Identify metal ions with flame tests and precipitates.

  • I can answer questions on today's skill on my own, without help.
  • I can explain each step and say why it works.
  • I can check my answer and spot a mistake.

Before and after

Needs first: Identify gases with laboratory tests

Leads to: the next skill in this area.

Materials: Teacher demo or video, Indicator color chart, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).

Warm-up · 6 min

  • Quick retrieval from earlier learning (Identify gases with laboratory tests). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Which gas gives this result: bubbled through limewater, it turns it milky? (hydrogen / oxygen / carbon dioxide / chlorine) → carbon dioxidePrompt: Each common gas has its own test.
  2. A gas puts out a lighted splint and turns limewater milky. What is it? (chlorine / carbon dioxide / oxygen / hydrogen) → carbon dioxidePrompt: Fire extinguishers sometimes contain this gas.
  3. Tests for gases: which statement is NOT true? (Oxygen relights a glowing splint. / Limewater is a solution of calcium hydroxide. / Hydrogen gives a squeaky pop with a lighted splint. / Carbon dioxide relights a glowing splint.) → Carbon dioxide relights a glowing splint.Prompt: Which gas pops and which relights a splint?

Hook · 6 min

  • Drop an antacid tablet in water (or show a clip) and ask whether a new substance is being made.
  • Share the objective: Identify metal ions with flame tests and precipitates. Read the success criteria together.

I do: model it · 12 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: A flame test gives a lilac flame. Which metal ion is present?
  • Step 1: Potassium compounds give a lilac flame.
  • Step 2: So the answer is: potassium, K⁺
  • Answer: potassium, K⁺
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 12 min

  • Do these together. Students try each step on whiteboards before you reveal it.
  • Use the hints as prompts rather than giving the answer.
  1. A flame test gives a lilac flame. Which metal ion is present? (sodium, Na⁺ / copper, Cu²⁺ / lithium, Li⁺ / potassium, K⁺) → potassium, K⁺Prompt: Fireworks use these colours.
  2. Sodium hydroxide solution is added to a solution and a white precipitate forms. Which metal ion is present? (copper(II), Cu²⁺ / iron(II), Fe²⁺ / iron(III), Fe³⁺ / calcium, magnesium or aluminium ions) → calcium, magnesium or aluminium ionsPrompt: Each transition metal ion gives its own coloured hydroxide.

You do: independent practice · 17 min

  • Students work on the student sheet. Circulate and check the first two answers of every student early.
  • Students who finish: write a question of their own for a partner, with the answer.

The 8 questions are on the student sheet below, with answers in the key.

Exit ticket · 7 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. A flame test gives a orange-red flame. Which metal ion is present? (sodium, Na⁺ / lithium, Li⁺ / calcium, Ca²⁺ / potassium, K⁺) → calcium, Ca²⁺Prompt: Fireworks use these colours.
  2. Sodium hydroxide solution is added to a solution and a green precipitate forms. Which metal ion is present? (copper(II), Cu²⁺ / iron(II), Fe²⁺ / iron(III), Fe³⁺ / calcium, magnesium or aluminium ions) → iron(II), Fe²⁺Prompt: Each transition metal ion gives its own coloured hydroxide.

Watch out for

  • Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
  • Remembering facts without the reason: ask "why?" and "what is the evidence?"

Support and stretch

Support

  • Review first: Identify gases with laboratory tests.
  • Use concrete materials: teacher demo or video.
  • Give the first step of each question, or a partly worked example to finish.
  • Pair with a confident partner for the guided practice.

Stretch

  • Explain a common mistake in writing and how to fix it.
  • Write a word problem that uses today's skill, then solve a partner's.

Homework and more practice

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-9.

Free lesson plan from eurekami.com/lesson-plan-builder

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Identify metal ions with flame tests and precipitates

Name

Date

Score/ 8

  1. Question 1

    Why can a flame test be hard to use for a mixture of sodium and potassium compounds?

    • A. Mixtures cannot be heated
    • B. Potassium does not give a flame colour
    • C. The bright yellow sodium flame can hide the lilac potassium colour
    • D. The colours combine into green

  2. Question 2

    A flame test gives a orange-red flame. Which metal ion is present?

    • A. sodium, Na⁺
    • B. calcium, Ca²⁺
    • C. lithium, Li⁺
    • D. potassium, K⁺

  3. Question 3

    Sodium hydroxide solution is added to a solution and a brown precipitate forms. Which metal ion is present?

    • A. copper(II), Cu²⁺
    • B. iron(II), Fe²⁺
    • C. iron(III), Fe³⁺
    • D. calcium, magnesium or aluminium ions

  4. Question 4

    Firework makers want a bright green colour. Which compounds should they add?

    • A. copper compounds
    • B. lithium compounds
    • C. potassium compounds
    • D. sodium compounds

  5. Question 5

    Sodium hydroxide solution is added to a solution and a green precipitate forms. Which metal ion is present?

    • A. copper(II), Cu²⁺
    • B. iron(II), Fe²⁺
    • C. iron(III), Fe³⁺
    • D. calcium, magnesium or aluminium ions

  6. Question 6

    What advantage does flame emission spectroscopy have over a flame test by eye?

    • A. It works only on gases
    • B. It needs no flame
    • C. It is more sensitive and can measure the concentration of ions
    • D. It is less accurate

  7. Question 7

    A flame test gives a yellow flame. Which metal ion is present?

    • A. copper, Cu²⁺
    • B. sodium, Na⁺
    • C. calcium, Ca²⁺
    • D. potassium, K⁺

  8. Question 8

    Sodium hydroxide solution is added to a solution and a white precipitate forms. Which metal ion is present?

    • A. copper(II), Cu²⁺
    • B. iron(II), Fe²⁺
    • C. iron(III), Fe³⁺
    • D. calcium, magnesium or aluminium ions

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Answer key: Identify metal ions with flame tests and precipitates

  1. 1. C. The bright yellow sodium flame can hide the lilac potassium colour

  2. 2. B. calcium, Ca²⁺

  3. 3. C. iron(III), Fe³⁺

  4. 4. A. copper compounds

  5. 5. B. iron(II), Fe²⁺

  6. 6. C. It is more sensitive and can measure the concentration of ions

  7. 7. B. sodium, Na⁺

  8. 8. D. calcium, magnesium or aluminium ions