The halogens show trends in their physical and chemical properties.
The halogens exist as simple molecules. Each molecule contains two halogen atoms joined by a single covalent bond. The table shows the colour and physical states of chlorine, bromine and iodine at room temperature.
|Chlorine, Cl2||Pale green||Gas|
The graph shows the melting and boiling points of the first four group 7 elements. Astatine is placed below iodine in group 7. Predict the melting and boiling points of astatine, and its state at room temperature.
Astatine should have a melting point of about 300 °C and a boiling point of about 340 °C. This means that it will be solid at room temperature.