Thermal Stability of Carbonates, Sulphates, and Nitrates of Alkali and Alkaline Earth Metals

1. Oxides vs. Carbonates, Sulphates, and Nitrates
- The thermal stabilities of carbonates, sulphates, and nitrates of alkali and alkaline earth metals are lower compared to their respective oxides.
- This is primarily due to the difference in the strength of the chemical bonds present in these compounds.

2. Chemical Bonds
- The oxides of alkali and alkaline earth metals are primarily ionic compounds with strong ionic bonds between the metal cation and oxide anion.
- In contrast, carbonates, sulphates, and nitrates of these metals contain covalent bonds in addition to ionic bonds.
- The presence of covalent bonds makes these compounds less stable at high temperatures compared to oxides.

3. Decomposition Temperatures
- Carbonates, sulphates, and nitrates decompose at lower temperatures compared to oxides when heated.
- Carbonates decompose to form metal oxides, carbon dioxide, and oxygen gas.
- Sulphates decompose to form metal oxides, sulfur dioxide, and oxygen gas.
- Nitrates decompose to form metal oxides, nitrogen dioxide, and oxygen gas.

4. Impact on Stability
- The presence of additional elements such as carbon, sulfur, and nitrogen in carbonates, sulphates, and nitrates weakens the overall stability of these compounds.
- This weakening effect leads to lower thermal stabilities compared to the more straightforward metal oxides.
In conclusion, the lower thermal stabilities of carbonates, sulphates, and nitrates of alkali and alkaline earth metals compared to their respective oxides can be attributed to the presence of covalent bonds and additional elements in these compounds.