Pearson Edexcel International GCSE Chemistry · specification 4CH1 · Paper 1 | Whole paper: Core content, all four topics · Free · no account needed
2(a) Group 1 (alkali metals) — lithium, sodium and potassium (4CH1 specification)
Three metals that react visibly with water, and a reactivity trend explained by one electron getting further from the nucleus.
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The Incandio page that teaches this — each explained in full, then proved in marked questions, taught back to an AI pupil and defended in a debate. Completely free.
- Group 1 — the Alkali Metals — Metals soft enough to cut with a knife, which set fire to water — and get worse as you go down.
The teaching route this belongs to: Topic 2 · Inorganic chemistry (Chemistry) — the lessons in order, with every gate.
Specification coverage
Topic 2 Inorganic chemistry (a) Group 1 (alkali metals) — lithium, sodium and potassium — statements 2.1–2.3
Assessment objectives: AO1, AO2. Suggested learning time: 45 minutes.
Required knowledge
- The reactions of lithium, sodium and potassium with water
- The pattern of reactivity down the Group
- The explanation of the trend in terms of electronic configuration and the ease of losing the outer electron
- Prediction of the properties of other members of the Group
Required skills
- Write balanced equations for the reactions with water
- Explain the trend rather than merely stating it
- Predict the behaviour of rubidium or caesium
How it is examined
- Multiple-choice and short-answer recall
- Application of the content to an unfamiliar context
- Extended open-response, marked on the quality of a connected explanation
Common mistakes
- Saying reactivity increases down the group 'because the atoms get bigger'. The mechanism is that the outer electron is further from the nucleus and more shielded, so it is lost more easily.
- Forgetting that hydrogen is produced as well as the hydroxide.
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