The halogens are elements in Group 7 of the Periodic Table.
Table 1 shows some properties of three halogens.
| Halogen | Electronegativity (Pauling scale) | Boiling point / K | State at room temperature |
|---|---|---|---|
| chlorine | 3.03.03.0 | 239239239 | gas |
| bromine | 2.82.82.8 | 332332332 | liquid |
| iodine | 2.52.52.5 | 457457457 | solid |
Astatine is located directly below iodine in Group 7.
Predict the physical state of astatine at room temperature.
Predict how the electronegativity of astatine compares with the electronegativity of iodine.
A student added bromine water to a colorless solution of potassium iodide.
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 bromine and potassium iodide:
Br2+2KI→………⋯+………… \text{Br}_2 + 2\text{KI} \rightarrow \dots\dots\dots\dots + \dots\dots\dots\dots Br2+2KI→………⋯+…………
