The halogens are elements in Group 7 of the Periodic Table.
Table 1 shows some properties of the first four halogens.
| Halogen | Appearance at room temperature | Boiling point in ∘C^\circ\text{C}∘C |
|---|---|---|
| fluorine | pale yellow gas | −188-188−188 |
| chlorine | pale green gas | −34-34−34 |
| bromine | red-brown liquid | 595959 |
| iodine | grey-black solid | 184184184 |
Astatine is located below iodine in Group 7.
Predict the physical state of astatine at room temperature.
Predict how the color of astatine compares with the color of iodine.
A student added chlorine water to a colorless solution of potassium bromide.
Describe the color change observed in the solution.
Explain why a reaction occurs, by comparing the reactivity of the halogens involved.
Complete the balanced chemical equation for the reaction between chlorine and potassium bromide:
Cl2+2KBr→………⋯+………… \text{Cl}_2 + 2\text{KBr} \rightarrow \dots\dots\dots\dots + \dots\dots\dots\dots Cl2+2KBr→………⋯+…………
