The table shows some properties of four Group 1 elements.
| Element | Density (g/cm3\text{g/cm}^3g/cm3) | Melting Point (°C) | Boiling Point (°C) |
|---|---|---|---|
| Sodium | 0.97 | 98 | 883 |
| Potassium | 0.86 | 63 | 759 |
| Rubidium | 1.53 | 39 | 688 |
| Caesium | 1.87 | 29 | 671 |
(i) State one trend in the properties of the Group 1 elements shown in the table.
(ii) Francium is below caesium in Group 1. Predict the melting point of francium using the information in the table.
The Group 1 elements all react with Group 7 elements to form ionic compounds.
(i) Explain why the Group 1 elements all react in the same way.
(ii) The Group 1 elements become more reactive down the group. Explain why.
(iii) Potassium reacts with chlorine, Cl2\text{Cl}_2Cl2, to make potassium chloride, KCl\text{KCl}KCl. Write the balanced symbol equation for this reaction.
Group 7 ions can be identified using silver nitrate solution. A student tests a compound for bromide ions. The diagram shows the student's experiment.
The student's experiment does not work to identify bromide ions. Explain why.