How atomic radius of group II metals is related to the trend in thermal decomposition of salts (group 2)?

Answer 1

The Group 2 carbonates decompose more easily at the top of the group than the bottom. The 2+ ions at the top of the group have a much smaller radius, with much more charge density. They therefore polarise the carbonate ions much more, making the metal carbonates at the top of the group much more covalent in character than those at the bottom. Thus they are much less stable to heat.

Answer 2

The atomic radii of atoms decrease moving right across the periodic table groups. This is because the core charge gradually increases since there is a stronger force of attraction between the valence electrons and the nucleus