Group 2

Question 1

Describe the trend in melting points down the group

Answer 1

• Melting points decrease down the group.

Question 2

Why does the melting point decrease down the group?

Answer 2

• The metallic bonding weakens as the atomic size
  increases.
• The distance between the positive ions and
  delocalized electrons increases.
• Therefore the electrostatic attractive forces between
  the positive ions and the delocalized electrons
  weaken.

Question 3

What happens when the group 2 elements react with cold water

Answer 3

Hydroxides are formed with the general formula:

M (s) + 2H2O (l) –> M(OH)2 (aq) + H2 (g)

Question 4

What are the observations when they react with cold water?

Answer 4

• fizzing, (more vigorous down group)
• the metal dissolving, (faster down group)
• the solution heating up (more down group)
• with calcium a white precipitate appearing (less
  precipitate forms down group with other metals)

Question 5

What’s the trend in hydroxide solubility down the group

Answer 5

• Group II hydroxides become more soluble down the
  group.
• All Group II hydroxides when not soluble appear as
  white precipitates
• The hydroxides produced make the water alkaline
  (if they are soluble in water) and the alkalinity will
  increase.

Question 6

Give the equation of Ba(OH)2 dissolving in water

Answer 6

Ba(OH)2 (S) + aq –> Ba2+ (aq) + 2OH-(aq)

Question 7

Write a simple ionic equation for the formation of Mg(OH)2 (s)

Answer 7

Mg2+(aq) + 2OH-(aq) —> Mg(OH)2(s).