Group 2 Metals

Question 1

What are the general trends of group 2 metals?

Answer 1

Down the group:
Atomic radii increases
Ionisation energy decreases
Electronegativity decreases
Reactivity increases

Question 2

What are the reactions with group 2 metals?

Answer 2

Metal + Water -> Metal Hydroxide + Hydrogen
Metal + Steam -> Metal Oxide + Hydrogen

Observations:
Bubbles/Colourless gas is given off
Metal Oxide forms a white solid

Question 3

Describe the solubility of Group 2 Metal Hydroxides.

Answer 3

Solubility increases down the group
Mg(OH)2 is partially soluble (White precipitate/Suspension)
Ba(OH)2 is insoluble

Note: A more soluble hydroxide will dissociate more in the solution and will thus be a stronger base.

Question 4

Describe the solubility of Group 2 Metal Sulfates.

Answer 4

Solubility decreases down the group
MgSO4 is soluble
BaSO4 is insoluble white precipitate

Question 5

Describe the thermal stability of Group 2 Metals.

Answer 5

Thermal Stability increases down the group because:
Charge density on the cation decreases down the group
Results in less distortion on the anion and a more stable compound

Question 6

What are the thermal decomposition reactions of Group 2 Metals?

Answer 6

MCO3 -> MO + CO2 Observation: Effervescence
M(OH)2 -> MO + H2O
2M(NO3)2 -> 2MO + 4NO2 + O2 Observation: Brown gas (NO2)

Question 7

What are the uses of Group 2 Compounds?

Answer 7

Calcium Hydroxide - Ca(OH)2 (Slaked lime) is used for neutralisation of acidic spills
Calcium Carbonate - CaCO3 is used as a construction material in buildings and is used to make cement
Magnesium Oxide - MgO is used as a refractory lining in kilns (because it is resistant to heat and retains its strength at very high temperatures)