Periodicity: Group 2, Alkaline Earth Metals - Reactions with Water

Question 1

Describe the change in oxidation states of group 2 metals when they react with water

Answer 1

• Group 2 elements are oxidised from a state of 0 to +2 forming M^2+ ions
• M → M^2+ + 2e^-

Question 2

Describe the general reaction between group 2 metals and cold water, including state symbols

Answer 2

• M (s) + 2H2O (l) → M(OH)2 (aq) + H2 (g)

Question 3

Give the reaction between magnesium and steam, including state symbols

Answer 3

• Mg (s) + H2O (g) → MgO (s) + H2 (g)

Question 4

Why are group 2 metals known as alkali metals?

Answer 4

• After reacting with water, the produced metal hydroxide form an alkaline solution
• The actual pH value is dependent of the solubility of the metal hydroxide

Question 5

How does the solubility of group 2 hydroxides change as you descend down group 2

Answer 5

• Solubility increases

- The more soluble a metal hydroxide is, the more basic the metal hydroxide is