Pearson Edexcel International GCSE Science Single Award 7: Chemistry: Inorganic chemistry
Pearson Edexcel International GCSE Science Single Award 4SS0 notes on chemistry: inorganic chemistry.
Topic 2 connects periodic patterns to observable reactions, atmospheric chemistry, metal reactivity, acids and analytical tests. These notes follow the Science Single Award points in Pearson 4SS0 Issue 4. They exclude halogen displacement, metal extraction, detailed salt preparation and ion tests reserved for broader routes.
Group 1 alkali metals
Lithium, sodium and potassium show similar reactions with water, supporting their classification as one chemical family. Each floats, moves on the surface, produces hydrogen and forms an alkaline metal hydroxide solution:
Reactivity increases down Group 1. Lithium reacts steadily, sodium more rapidly and potassium can ignite with a lilac flame. Their reactions with air also become more vigorous. Use this trend to predict that rubidium would react even more vigorously, while preserving the family's common formation of positive ions and alkaline hydroxides.
A trend prediction should separate evidence from extrapolation. Results for lithium, sodium and potassium support the pattern, but the prediction for another element is not a direct observation.
Group 7 halogens
At room temperature, chlorine is a pale green gas, bromine a red-brown liquid and iodine a grey solid that forms purple vapour when heated. Down Group 7, colour darkens, melting and boiling points increase, and physical state changes from gas to liquid to solid. These trends allow predictions for another halogen, such as a darker, higher-boiling element below iodine.
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