Why don't all the Group 1 metal carbonates decompose in the lab?
Answer (2)
Not all group 1 metal carbonates decompose in the lab because their stability is influenced by the size and polarizing ability of the metal cation. As the size of the alkaline earth metal cation increases from Be to Ba, its ability to polarize the carbonate anion decreases. This makes it more difficult for larger cations to decompose the carbonate, which would otherwise produce carbon dioxide and a metal oxide.
Group 1 metals form carbonates with the general formula M₂CO₃, where M represents a group 1 metal. Examples of these carbonates include sodium carbonate (Na₂CO₃) and potassium carbonate (K₂CO₃). These carbonates do not readily decompose at the temperatures usually used in lab settings.
The thermal stability of group 1 metal carbonates is due to the low charge density of their ions, which exerts less polarization on the carbonate ion. As a result, Group 1 carbonates are more stable to heat than, for example, group 2 metal carbonates, which decompose more readily to form metal oxides and carbon dioxide gas.
Group 1 metal carbonates do not decompose easily in the lab due to the large size and low polarizing ability of their cations, which stabilizes the carbonate anion. Their thermal stability requires higher temperatures for decomposition compared to other groups. As a result, they remain stable under typical laboratory heating conditions.
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