Explain what is meant by the term standard enthalpy change of atomisation.
For fluorine and chlorine, the enthalpy changes of atomisation are half the bond energies. For bromine and iodine, the enthalpy changes of atomisation are much more than half the bond energies. Suggest a reason for this difference.
The standard enthalpy of formation of iodine monochloride, $\text{ICl}$, is $-24.0\,\text{kJ mol}^{-1}$. Use this together with the bond energies of iodine and chlorine to calculate the I-Cl bond energy.
Explain the pattern in the boiling points of the hydrogen halides, HCl, HBr and HI.
Suggest why the hydrogen halide HF does not follow the boiling point trend shown by HCl, HBr and HI.
Identify the halogens $\text{P}_2$ and $\text{Q}_2$.
HP readily decomposes into its elements on heating but HQ is stable to heat. Explain this in terms of bond energies.
Write an equation for the thermal decomposition of HP.
Write ionic equations, including state symbols, for (1) the formation of the white precipitate when aqueous silver ions are added to aqueous HQ, and (2) the later dissolution of this precipitate in dilute aqueous ammonia.
State and explain the pattern shown by the formulae of the three chlorides $\text{MgCl}_2$, $\text{AlCl}_3$ and $\text{SiCl}_4$.
Write equations to show what happens when each of these chlorides is added to water: $\text{MgCl}_2$, $\text{AlCl}_3$ and $\text{SiCl}_4$.