4.4.2 Physical Properties of Group 17 Elements

1. All group 17 elements are non-metals. Therefore they are heat and electricity insulator.
2. The table below shows the electron arrangement and physical properties of group 17 elements.

Size of Atom and Density

1. The atomic size of group 17 elements increases down the group.
2. This is due to the increase of the number of electron shell down the group.
3. The density of group 17 elements also increase down the group.
4. This is because the rate of increment of the atomic mass is higher than the rate of increment of the volume.

Melting Point and Boiling Point

1. As shown in the graph to the right, the melting points and boiling increase steadily down the group.
2. The physical state at room temperature also change from gas to liquid and then to solid.
3. This is because of the intermolecular attractive force (van der Waals force) increase with increasing size of atom or molecule.