PERIODICITY (group 17)

Question 1

State and explain the changes in volatility down the group

Answer 1

Volatility decreases down the group.

Halogens are non-polar simple covalent molecules with weak instantaneous dipole-induced dipole interactions between its molecules.

Down the group, the number of electrons per molecule increases, increasing electron cloud size of X2.

Question 2

State and explain the changes in thermal stability

Answer 2

Thermal stability decreases down the group.

Down the group, the size of halogens increase, and the valence orbital used for bonding is larger and more diffuse. The extent of orbital overlap between the 1s orbital and the valence p orbital X atoms decreases

The electronegativity difference between the hydrogen and halogen decreases, decrease in bond polarity. H-X bond strength decreases and less energy is required to break the bond.