3.2.2 Group 2

Question 1

Describe and explain the trends in IE down group 2.

Answer 1

IE decreases down group 2
- Atomic radius increases down group
- Shielding increases
- Outer elctrons further from nucleus, requires less energy to remove electron

Question 2

Describe and explain the trend in melting points down group 2.

Answer 2

M.p decrease down group
- Ion charge is constant (2+)
- Ionic radius increases down group
- More shielding
- Weaker attraction between positive metal ions and delocalised electrons

Question 3

State and explain the trend with reactivity in water of the elements down group 2.

Answer 3

Increasing reactivity with water down group
- More shielding, larger atomic radius
- Weaker attraction between outer electron and nucleus

Question 4

Write an equation for the reaction of water and strontium.

Answer 4

2H2O + Sr → Sr(OH)2 + H2

Question 5

What are the following group 2 elements/compounds used for:
a) barium sulfate
b) magnesium hydroxide
c) calcium hydroxide
d) magnesium
e) calcium

Answer 5

a) Barium meal (x-rays)
b) Milk of magnesia (neuralise stomach acid)
c) Slaked lime (neutralise acidic soil)
d) Extracting Ti from TiO2
e) Calcium carbonate (extract sulfur from flue gases)

Question 6

Describe the solubilities of sufates of group 2 (Mg→Ba)

Answer 6

MgSO4 = soluble
CaSO4 = slightly soluble
SrSO4 = insoluble
BaSO4 = insoluble

Question 7

Describe the solubilities of hydroxides of group 2 (Mg→Ba)

Answer 7

Mg(OH)2 = insoluble
Ca(OH)2 = slightly soluble
Sr(OH)2 = soluble
Ba(OH)2 = soluble

Question 8

How would you distinguish between aqueous MgCl2 and BaCl2?

Answer 8

• Add NaOH
• Solution containing BaCl2 will go colourless
• Solution containing MgCl2 will form a white ppt

Question 9

Write an equation for the reaction between strontium chloride solution and sodium sulfate solution. Include state symbols.

Answer 9

SrCl2 (aq) + Na2SO4 (aq) → SrSO4 (s) + 2NaCl (aq)