The table shows the colour and physical states of chlorine, bromine and iodine at room temperature and pressure.
|Group 7 element||Colour||State||Colour in gas state|
The bond between the atoms in a molecule is very strong, but the forces of attraction between molecules are weak. This explains why group 7 elements have low boiling points.
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. (Actual boiling point is 350°C.)