This topic summary covers Knowledge Organiser: Group 1 Alkali Metals within Group 1: Alkali Metals for GCSE Chemistry. Revise Group 1: Alkali Metals in Atomic Structure for GCSE Chemistry with 22 exam-style questions and 20 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 13 of 13 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Knowledge Organiser: Group 1 Alkali Metals
Key Terms
- Alkali metals: Group 1, 1 outer electron
- Reactivity trend: Increases down Group 1
- Shielding: Inner electrons reduce nuclear pull
- Metal hydroxide: Product of water reaction
Must-Know Facts
- Soft, low density, low melting point
- Stored under oil (prevent air/water reaction)
- React with water → hydroxide + hydrogen
- 2Na + 2H₂O → 2NaOH + H₂
- React with chlorine → metal chloride (e.g., 2Na + Cl₂ → 2NaCl)
- Li: gentle fizz; Na: vigorous; K: lilac flame
- Reactivity increases ↓ (outer electron further, weaker attraction)
Key Equations
- 2Li + 2H₂O → 2LiOH + H₂
- 2Na + 2H₂O → 2NaOH + H₂
- 2K + 2H₂O → 2KOH + H₂
- 2Na + Cl₂ → 2NaCl
Common Mistakes
- Forgetting hydrogen gas is produced: Alkali metals + water → metal hydroxide AND hydrogen — both products are needed for full marks
- Saying reactivity decreases down Group 1: It increases — the outer electron is further from the nucleus and more easily lost
- Missing the 2 coefficient: The equation is 2Na + 2H₂O → 2NaOH + H₂ — students often write Na + H₂O → NaOH + H
- Saying melting points increase down Group 1: They decrease — larger atoms have weaker metallic bonding
Practice questions for Group 1: Alkali Metals
How many electrons do alkali metals have in their outermost shell?
Explain why potassium is more reactive than sodium when it reacts with water.
Quick recall flashcards
More reactive: Li or K?
Potassium (further down = more reactive)
Equation: sodium + water →
2Na + 2H₂O → 2NaOH + H₂