A teacher wants to demonstrate the reactions of three alkali metals (lithium, sodium, and potassium) with water to a class.
Before the demonstration, they construct a table of expected observations:
| Metal | Behavior on water | Speed of movement | Other observations |
|---|---|---|---|
| Lithium | Floats on the surface | Slow | Fizzes steadily, gradually dissolves |
| Sodium | Floats and melts into a sphere | Fast | Fizzes rapidly, moves quickly across the surface |
| Potassium | Floats and melts | Very fast | Fizzes violently, burns with a lilac flame |
Describe, in detail, how the teacher should safely perform this demonstration and explain how the observations from the table show the order of reactivity of the three metals.
75 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.