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Science lesson plan Β· 9th grade (Year 10 in England) Β· 30 minutes

Predict ion charges from the periodic table

Atoms, elements and the periodic table

CCSS NGSS.HS-PS1-1CCSS NGSS.HS-PS1-2England: GCSE Combined Science: Bonding, structure and the properties of matter

Objective and success criteria

Students will: Predict ion charges from the periodic table.

  • 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: Electron shells and the periodic table

Leads to: Build ionic formulae from ion charges

Materials: Periodic tables, Atom model kits, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).

Warm-up Β· 4 min

  • Quick retrieval from earlier learning (Electron shells and the periodic table). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. How many electrons does an atom of magnesium (atomic number 12) have in its outer shell? β†’ 2Prompt: Fill the shells 2, 8, 8 in order.
  2. Who arranged the elements in an early periodic table and left gaps for undiscovered elements? (Charles Darwin / Marie Curie / Dmitri Mendeleev / Isaac Newton) β†’ Dmitri MendeleevPrompt: He predicted the properties of gallium and germanium before they were found.
  3. How many electrons does an atom of lithium (atomic number 3) have in its outer shell? β†’ 1Prompt: Fill the shells 2, 8, 8 in order.

Hook Β· 3 min

  • Show the periodic table and ask what patterns students can see before anything is explained.
  • Share the objective: Predict ion charges from the periodic table. Read the success criteria together.

I do: model it Β· 7 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: Phosphorus (P) is in group 15 (5). What charge does its ion have?
  • Step 1: It gains 3 electrons, so the ion is negative.
  • Step 2: So the answer is: 3βˆ’
  • Answer: 3βˆ’
  • Pause after each step and ask a student to say what comes next.

We do: guided practice Β· 6 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. Potassium (K) is in group 1. What charge does its ion have? (2βˆ’ / 1βˆ’ / 1+ / 2+) β†’ 1+Prompt: Metals lose their outer electrons; non-metals gain electrons to fill their outer shell.
  2. An atom of aluminium (atomic number 13) forms its usual ion (charge 3+). How many electrons does the ion have? β†’ 10Prompt: A neutral atom has as many electrons as protons.

You do: independent practice Β· 7 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 6 questions are on the student sheet below, with answers in the key.

Exit ticket Β· 3 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. An atom of calcium (atomic number 20) forms its usual ion (charge 2+). How many electrons does the ion have? β†’ 18Prompt: A neutral atom has as many electrons as protons.
  2. Aluminium (Al) is in group 13 (3). What charge does its ion have? (3+ / 2βˆ’ / 2+ / 3βˆ’) β†’ 3+Prompt: Metals lose their outer electrons; non-metals gain electrons to fill their outer shell.

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: Electron shells and the periodic table.
  • Use concrete materials: periodic tables.
  • Give the first step of each question, or a partly worked example to finish.
  • Pair with a confident partner for the guided practice.

Stretch

  • Move on to: Build ionic formulae from ion charges.
  • 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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Predict ion charges from the periodic table

Name

Date

Score/ 6

  1. Question 1

    Fluorine (F) is in group 17 (7). What charge does its ion have?

    • A. 2βˆ’
    • B. 3+
    • C. 1+
    • D. 1βˆ’
  2. Question 2

    An atom of sulfur (atomic number 16) forms its usual ion (charge 2βˆ’). How many electrons does the ion have?

    Answer

  3. Question 3

    Why does solid sodium chloride not conduct electricity, but molten sodium chloride does?

    • A. Heat conducts electricity
    • B. In the liquid the ions are free to move and carry charge
    • C. Melting creates electrons
    • D. The solid has no ions
  4. Question 4

    Magnesium (Mg) is in group 2. What charge does its ion have?

    • A. 1+
    • B. 3βˆ’
    • C. 1βˆ’
    • D. 2+
  5. Question 5

    Sulfur (S) is in group 16 (6). What charge does its ion have?

    • A. 1βˆ’
    • B. 3+
    • C. 3βˆ’
    • D. 2βˆ’
  6. Question 6

    An atom of oxygen (atomic number 8) forms its usual ion (charge 2βˆ’). How many electrons does the ion have?

    Answer

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Answer key: Predict ion charges from the periodic table

  1. 1. D. 1βˆ’

  2. 2. 18

  3. 3. B. In the liquid the ions are free to move and carry charge

  4. 4. D. 2+

  5. 5. D. 2βˆ’

  6. 6. 10