Question

Why does thermal stability of elements increase down a group in a periodic table. Shouldn't it decrease because the elements lower in the periodic table can easily lose electrons and form compounds therefore having low stability?

Thanks a lot.

Answer 1

Group 1 compounds are more stable to heat than the corresponding compounds ... The decomposition temperatures again increase as you go down the Group. ... Inorganic Chemistry (my copy published in 1960) says that it will decompose on ...

Answer 2

All the carbonates in this group undergo thermal decomposition to the metal oxide and carbon dioxide gas. The term "thermal decomposition" describes splitting up a compound by heating it.
All the Group 2 carbonates and their resulting oxides exist as white solids. If "X" represents any one of the elements, the following describes this decomposition:XCO3(s)→XO(s)+CO2(g)
Down the group, the carbonates require more heating to decompose.The carbonates become more thermally stable down the group.
Down the group, the nitrates must also be heated more strongly before they will decompose.