Thermal Stability of all Alkaline Earth Metals

↪ When alkaline earth metal carbonates and nitrates are heated, they decompose to give metal oxides as,

↪ The oxides ion are more strongly attracted to metal ions in the crystals lattice than CO₃^2- and NO₃^- ions because the charge density in small O^2- ion is greater than that in large ions, CO₃^2- and SO₄^2-.
↪ Therefore alkaline earth metal carbonates and nitrates are decomposed thermally to give more stables crystals of metal oxides.

↪ The general trend of stability of carbonates and nitrates is described briefly:

1. Stability of carbonate
↪ Carbonates of alkaline earth metals are fairly stable to heat.
↪ The thermal stability of carbonates goes on increasing from top to bottom along group.
The general trend is:
BeCO₃ < MgCO₃ < CaCO₃ < SrCO₃ < BaCO₃

2. Stability of nitrate
↪ The thermal stability of metal nitrates increases from top to bottom in the group.
↪ The general trend of thermal stability of nitrates is:
Ba(NO₃)₂ > Sr(NO₃)₂ > Ca(NO₃)₂ > Mg(NO₃)₂ > Be(NO₃)₂