Group 2

Question 1

atomic radius trend down group

Answer 1

• gets bigger

- more shells of electrons making atoms bigger

Question 2

1st ionisation energy down group

Answer 2

• gets lower
• atomic radius bigger
• more shielding
• attraction between nucleus + outer shell electron decreases down group

Question 3

Melting points down group

Answer 3

• gets lower
• metallic bonding weakens as atomic size increases
• distance between ions + delocalised electrons increases
• electrostatic attractive forces weaken

Question 4

Trend in reactivity down group

Answer 4

More reactive

Question 5

Mg reaction with water

Answer 5

• no reaction with cold water (very slow)
• burns with white flame to form white powder with steam
• Mg + 2H2O -> MgO + H2

Question 6

Ca reaction with water

Answer 6

• Fizzes and forms white solid (Ca(OH)2) after time
• solid is slightly insoluble in water
• Ca + 2H2O -> Ca(OH)2 + H2

Question 7

Sr or Ba reaction with water

Answer 7

• Fizzes in water and forms colourless solution
• Ba + 2 H2O -> Ba(OH)2 + H2
• Sr + 2 H2O -> Sr (OH)2 + H2

Question 8

Explanation of metal + water trend

Answer 8

• metals react abs lose their two outer shell electrons
• atoms get bigger and there is more shielding down group
• so weaker attraction between nucleus and outer shell electron so outer sell electrons are more easily lost

Question 9

Harder/ softer down group

Answer 9

Softer

Question 10

Why is it dangerous to put out a Mg fire using water?

Answer 10

Mg reacts with water at high temps to produce hydrogen gas which is explosive

Question 11

Equation for reaction to extract titanium from titanium chloride using magnesium

Answer 11

TiCl4 + 2Mg -> Ti + 2MgCl2

Question 12

Solubility trend down group of hydroxides

Answer 12

Get more soluble

Question 13

Calcium hydroxide use in agriculture

Answer 13

Neutralises acidic soils

Question 14

Medical use of magnesium hydroxide

Answer 14

Milk of magnesia

- neutralises excess acid in stomach to treat constipation

Question 15

What substance removes sulfur dioxide from flue gases?

Answer 15

• Calcium oxide or calcium carbonate because they are basic substances and sulfur dioxide is acidic
• a neutralisation or acid-base reaction

Question 16

Solubility trend down group of sulfates

Answer 16

Gets less soluble

Question 17

Barium sulfate medical use

Answer 17

Uses in barium meal (medicine)

- intestine x-rays to make intestines more visible

Question 18

How can barium sulfate be used even though it is highly toxic?

Answer 18

Has low solubility so means isn’t absorbed into blood

Question 19

Which ions is barium chloride used to test for? What would the result of a positive test be?

Answer 19

Sulfate ions would produce a white precipitate in the presence of barium chloride dies to formation of barium sulfate

Question 20

Why must the solution be acidified with hydrochloric acid before the test for presence of sulfate ions is carried out?

Answer 20

To remove ions such as carbonate ions that would give a false positive result of white precipitate

Question 21

What is a method to identify and distinguish sample of calcium strontium and barium ions?

Answer 21

• Take sample of each metal ion + add sodium hydroxide to it
• resulting solutions can be distinguished based on which forms precipitates -
  Calcium hydroxide- sparing soluble
  Strontium hydroxide - more soluble
  Barium hydroxide - more soluble

Question 22

Hydroxide solubility general equation

Answer 22

X2(aq) + 2OH- (aq) -> X(OH)2(s)

Question 23

Sulfate solubility general equation

Answer 23

X2+ (aq) + SO4 2- (aq) -> XSO4 (s)