c2 the periodic table
4 detailed 50-minute lessons with teaching scripts, worked examples, parent guides, and assessment criteria.
4 detailed 50-minute lessons with teaching scripts, worked examples, parent guides, and assessment criteria.

Write down everything you already know about c2 the periodic table. Then check against the key terms: Periodic table, Group, Period. Use a mini-whiteboard or paper.
Start with the revision notes summary, then attempt: Foundation Describe two ways Mendeleev arranged elements in his periodic table and explain why his table was accepted by other scientists.
Your student states one thing they learned and one question they still have about c2 the periodic table.
Quick recap: write 3 key points from Lesson 1 on c2 the periodic table. Check them against the notes below.
| Term | Meaning | Example |
|---|---|---|
| Arranged by | Atomic mass | Atomic number |
| Gaps left | Yes - for undiscovered elements | No - all known elements placed |
| Swapped elements | Yes (e.g. iodine and tellurium) | No - atomic number order resolves this |
| Predictions | Made predictions for undiscovered elements | Not needed |
| Fluorine (F₂) | Pale yellow | Gas |
| Chlorine (Cl₂) | Green-yellow | Gas |
| Bromine (Br₂) | Red-brown | Liquid |
| Iodine (I₂) | Dark grey/violet | Solid |
Q: Foundation Describe two ways Mendeleev arranged elements in his periodic table and explain why his table was accepted by other scientists.
Answer: Mendeleev arranged elements in order of atomic mass and put elements with similar properties in the same group. He left gaps for undiscovered elements and predicted their properties. His table was accepted because when the missing elements were discovered, their properties matched his predictions.
Your student teaches the key points back to you without looking. Fill any gaps immediately.
Recall the key terms: Periodic table, Group, Period. Define each in one sentence.
Q1: Foundation Describe two ways Mendeleev arranged elements in his periodic table and explain why his table was accepted by other scientists.
Answer: Mendeleev arranged elements in order of atomic mass and put elements with similar properties in the same group. He left gaps for undiscovered elements and predicted their properties. His table was accepted because when the missing elements were discovered, their properties matched his predictions.
Q2: Foundation Explain why alkali metals become more reactive as you go down the group.
Answer: As you go down Group 1, the outer electron is further from the nucleus and there are more inner electron shells providing shielding. This means the outer electron is less strongly attracted to the nucleus and is lost more easily, making the atom more reactive.
Q3: Foundation Write a word equation and a symbol equation for the reaction of sodium with water. What observations would you make?
Answer: Word equation: sodium + water → sodium hydroxide + hydrogen. Symbol equation: 2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g). Observations: sodium melts into a ball, fizzes rapidly, moves quickly on the water surface.
Q4: Higher Chlorine is added to a solution of potassium iodide. State what happens and explain why. Write a symbol equation for the reaction.
Answer: Chlorine displaces iodine from potassium iodide because chlorine is more reactive than iodine (it is higher in Group 7). The solution turns brown/violet as iodine is released. Equation: Cl₂(aq) + 2KI(aq) → 2KCl(aq) + I₂(aq).
Q5: Foundation Explain why noble gases are unreactive and give one use of argon.
Answer: Noble gases are unreactive because they have full outer electron shells, so they do not need to gain, lose or share electrons. Argon is used in welding to provide an inert atmosphere that prevents the hot metal reacting with oxygen in the air.
Q6: Higher Compare the properties of alkali metals with transition metals. Give at least three differences.
Answer: Three differences: (1) Alkali metals are very reactive, transition metals are much less reactive. (2) Alkali metals have low melting points, transition metals have high melting points. (3) Alkali metals are soft (can be cut with a knife), transition metals are hard and strong. (4) Transition metals form coloured compounds, alkali metals form white compounds. (5) Many transition metals are good catalysts; alkali metals are not.
Review any questions answered incorrectly. Identify whether the error was knowledge, method, or reading the question.
Review what these command words require: state (one point), describe (say what happens), explain (say why), compare (both sides), evaluate (judgement).
Extended question: Extended Answer 6 marks: Explain the reactivity trends in Group 1 and Group 7. <div class="
Group 1 reactivity increases down the group because the outer electron is further from the nucleus and more shielded by inner electron shells, so it is lost more easily. Group 7 reactivity decreases down the group because the outer shell is further from the nucleus and more shielded, so the atom finds it harder to attract an extra electron. Both trends are explained by increasing atomic size and shielding, but the outcome differs because Group 1 loses an electron (easier further out) while Group 7 gains one (harder further out). Mark scheme: 1 mark for Group 1 trend; 1 mark for Group 1 explanation (distance + shielding); 1 mark for Group 7 trend; 1 mark for Group 7 explanation (distance + shielding); 1 mark for linking both to outer electron; 1 mark for contrasting loss vs gain of electrons.
You are ready for c2 the periodic table - GCSE Combined Science (Trilogy) Lessons when you can:
Tick each item honestly — if any box is unticked, re-read the relevant section above.
This lesson is examined by: AQA 8464 | Edexcel 1SC0 | OCR J250 | CCEA units. Tier and paper details vary - always check your board's current specification.
Follow-up revision: C2-the-periodic-table on GCSE Revise (notes, flashcards and auto-graded target tests for this exact topic).
Parent/teacher: Draw a central circle (nucleus) and write p+ and n0 inside. Draw a dashed circle around it (first shell). Place 2 electrons on the shell. For the second shell, place up to 8 electrons.
Display the reference diagram (or draw it live) while pupils copy. Check each label as it is added.