2.7.1e: recall the trends in thermal stability of the nitrates and the carbonates of the elements in groups 1 and 2 and explain these in terms of size and charge of the cations involved

Carbonates and nitrates of group 1 and 2 become more thermally stable as you go down the groups

• this is because the larger the size of the metal ion, the more stable the metal carbonate or nitrate
• the smaller metal ions have the highest charge density, so cause greater polarisation of the anion, helping it to break down

Group 2 elements have a greater charge than group 1 elements, so their nitrates and carbonates are less stable