Group 2

Question 1

Explain how the first ionisation energy changes going down Group 2

Answer 1

Decreases
Extra shell of electrons added
Increased shielding
Weaker electrostatic attraction between the outer electron and nucleus
Less energy to lose first outer electron

Question 2

How does the melting point of Group 2 change going down?

Answer 2

Decrease
Extra shell of electrons
Increase shielding
Metallic bonding is weaker as the ions are larger so there is a weaker attraction between nucleus and delocalised electrons
Weaker bonds —> lower melting point

Question 3

What is the trend in atomic radius going down Group 2?

Answer 3

Increase
Extra shell of electrons added
Increased shielding
Weaker electrostatic attraction between outer electron and nucleus
Allows the rings to ‘drift’ further out

Question 4

Use of Magnesium Hydroxide Mg(OH)2

Answer 4

Alkaline nature, used in medicine for digestive upsets + laxative
Main ingredient in ‘milk of magnesia’

Question 5

Use of Calcium Hydroxide Ca(OH)2

Answer 5

Alkaline nature
Agriculture to neutralise acidic soils

Question 6

Use of Calcium Oxide (CaO) and Calcium Carbonate (CaCO3)

Answer 6

React with flume gases. To remove sulphur dioxide preventing acid rain.

Question 7

Use of Barium Sulphate (BaSO4)

Answer 7

Part of ‘barium meal’
Given to patients for an X-ray of the digestive system
Insoluble - not absorbed by the bloodstream

Question 8

Magnesium (Mg)

Answer 8

Reduce titanium from titanium chloride - its a more reactive metal
2Mg + TICl4 —> 2MgCl2 + TI

Question 9

What is the solubility of Group 2 Hydroxides and Sulphates as you go down the group?

Answer 9

Hydroxides - increase in solubility
Sulphates - decrease in solubility

Question 10

Calcium with water equation

Answer 10

Ca + 2H20 —> Ca(OH)2 + H2

Question 11

Magnesium with water equation

Answer 11

Mg + H20 —> MgO + H2

Question 12

Testing for Sulphates

Answer 12

Unknown solution/sample
Add hydrochloric acid (removes false positive white precipitates)
Add barium chloride (BaCl2)
BaCl2 + XSO4 —> BaSO4 + XCl

Question 13

State the trends in solubility of the hydroxides and of the Sulphates of the group 2 elements Mg-Ba.
Describe a chemical test you could perform to distinguish between separate aqueous solutions of sodium sulphate and sodium nitrate.
State the observation you would make with each solution.
Write an equation for any reaction which occurs.

Answer 13

Hydroxides - solubility increases
Sulphates - solubility decreases
Add BaCl2
With Na2SO4, white precipitate is formed
NaNO3, no change
BaCl2 + Na2SO4 —> BaSO4 + 2NaCl