A teacher adds pieces of lithium, sodium and potassium of the same size to separate troughs of water. The teacher measures the time taken for each piece of metal to disappear.
| Alkali metal | Electronic configuration | Time taken to disappear / s |
|---|---|---|
| lithium | 2.1 | 55 |
| sodium | 2.8.1 | 12 |
| potassium | 2.8.8.1 | 3 |
Suggest why the teacher uses pieces of metal of the same size.
Predict the time taken for a piece of rubidium of the same size to disappear.
Suggest why the teacher does not demonstrate the reaction of rubidium with water.
Explain the trend in reactivity of the alkali metals shown by the data. Use the observations you would expect and the electronic configurations in your answer.
41 exam-style questions on Edexcel GCSE Chemistry 7.1 Group 1, covering 7.1.1 Classifying elements by group in the periodic table and 7.1.2 Properties and reactions of the alkali metals. Each one has a worked solution and a mark scheme showing where the marks go.