A laboratory technician is preparing a video demonstration comparing the reactions of three Group 1 metals: sodium, potassium, and rubidium with water.
They compile a reference table of physical properties and expected behaviors:
| Metal | Density (g cm−3\text{g cm}^{-3}g cm−3) | Melting point (∘C^\circ\text{C}∘C) | Behavior on/in water | Other observations |
|---|---|---|---|---|
| Sodium | 0.97 | 98 | Floats and melts into a silver sphere | Fizzes rapidly, moves quickly, dissolves |
| Potassium | 0.86 | 63 | Floats and melts instantly | Fizzes violently, ignites spontaneously with a lilac flame |
| Rubidium | 1.53 | 39 | Sinks rapidly | Reacts explosively, shattering the vessel if not carefully controlled |
Describe, in detail, the essential safety protocols the technician must implement to perform this demonstration safely, and explain how the physical properties (density and melting point) and chemical observations in the table show the trend in reactivity and behavior down Group 1.
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.