Group 2

Question 1

Explain the trend of reactivity down group 2

Answer 1

• number of protons increases hence nuclear charge increases
• Down the group, the number of shells increases and valence electrons are further away from the nucleus hence shielding effect increases
• Effective nuclear charge decreases and valence electrons are less strongly attracted to the nucleus
• Less energy required to remove valence electrons
• E becomes more negative
• reducing power increases ( and reactivity increases)

Question 2

Explain the trend of thermal stability of group 2 carbonates

Answer 2

• ionic radius of group 2 cation increases
• charge density and polarising power decreases
• electron cloud of carbonate anion distorted less
• C-O bond in carbonate ion weakened to a smaller extent
• Thermal stability of group 2 carbonate increases