Group 2

Question 1

Describe the melting points of group 2 elements

Answer 1

High - They have many strong metallic bonds (attractions between positive metal ions and delocalised electrons). - These take a lot of energy to break

Question 2

Describe the density of group 2 elements compared to group 1

Answer 2

Higher - Group 2 ions are smaller than group 1 ions so they can pack more closely

Question 3

Why are group 2 elements reactive metals with similar chemical reactions?

Answer 3

They all have two outer electrons which are lost during reactions

Question 4

What is the appearance of group 2 compounds?

Answer 4

White crystalline solids

Question 5

What is the type of bonding for group 2 compounds?

Answer 5

Ionic

Question 6

Describe the trend in atomic radius down group 2.

Answer 6

Increases Shielding increases as there are more shells Distance from the nucleus increases as there are more shells Nuclear charge increases but this effect is small compared to the other factors So the nuclear attraction to the outer electrons is less and so atomic radius increases

Question 7

Describe the trend in first ionisation energy down group 2

Answer 7

Decreases Shielding increases as there are more shells Distance increases as there are more shells Nuclear charge increases So the nuclear attraction to outer electrons is less and so less energy is needed to remove it

Question 8

Describe the trend in melting points down group 2

Answer 8

Decreases Group 2 elements have giant metallic structures. As you go down the group the ions get larger so the attraction to delocalised electrons gets less and so the metallic bonds get weaker.

Question 9

Describe the trend in reactivity down group 2.

Answer 9

Increases Group 2 metals react by losing their outer electrons. Shielding increases as the number of shells increases. This means the nuclear attraction to the outer electrons is less and they get lost more easily

Question 10

Describe the observations and products when you react Mg with cold water and steam.

Answer 10

Cold water: -Very very slow bubbling - H2(g) + Mg(OH)2(s) Steam: -White glow & white solid formed -H2 (g) + MgO (s)

Question 11

Describe the observations and products when you react Ca with cold water.

Answer 11

-Fizzing, white solid of slightly soluble Ca(OH)2 but some Ca(OH)2 dissolves to leave an alkaline solution - H2 (g) + Ca(OH)2 (aq)

Question 12

Describe the observations and products when you react Sr with cold water.

Answer 12

Fizzing, less white solid formed as Sr(OH)2 is more soluble H2(g) + Sr(OH)2 (aq)

Question 13

Describe the observations and products when you react Ba with cold water.

Answer 13

Fizzing No white solid as Ba(OH)2 (aq) is soluble H2 (g) + Ba(OH)2 (aq)

Question 14

Describe the general trend for the reaction between group 2 elements and water as you go down the group

Answer 14

Increases

Question 15

What is the equation for the reaction between Mg and steam?

Answer 15

Question 16

What is the equation for the reaction between any group 2 metal and cold water? Describe the change in oxidation number. Construct half equations.

Answer 16

Question 17

Why is titanium a useful metal?

Answer 17

Its strong

It has a high melting point

It has high corrosion resistance

Question 18

Why is titanium difficult to extract from its ores?

Answer 18

Reduction with carbon produces brittle TiC

Question 19

Describe how titanium is extracted from its ore.

Answer 19

It is first reacted with chlorine and carbon to form titanium chloride TiCl4

It is then reduced with magnesium to produce titanium

Question 20

What are the equations for the extraction of titanium?

Answer 20

Question 21

What is the general equation for the reaction between group two hydroxide and hydrochloric acid? What does the hydroxide act as?

Answer 21

A base

Question 22

What is the general equation for the reaction between group 2 hydroxides and H2SO4? What does the hydroxide act as?

Answer 22

A base

Question 23

Describe the trend in in formula, solubility and pH of the group 2 hydroxides.

Answer 23

As you go down the group:

• Formula - M(OH)2
• Solubility - increases
• pH - increases (from 8 to 13)

Question 24

How do you test the relative solubility of group 2 hydroxides?

Answer 24

Add aqueous sodium hydroxide.

Magnesium hydroxide is sparingly soluble and so a thich white ppt should be seen

Barium hydroxide is much more soluble and so a thin white ppt would be seen.

Question 25

What are the uses of magnesium hydroxide?

Answer 25

Milk of magnesia contains Ca(OH)2 which is used to neuralise stomach acid

Ca(OH)2 is used to neutralise acidic soil

Question 26

Describe the trend in formula and solubility of group 2 sulfates

Answer 26

Formula: MSO4 (where M is any group 2 metal)

Solubility: decreases down group 2.

Question 27

How do you test the relative solubility of group 2 sulfates? What is he equation (use Sr)

Answer 27

Add sulfuric acid or aqueous sodium sulfate.

MgSO4 is soluble and so no ppt will form

BaSO4 is insoluble and so a thick white ppt will form

Question 28

How do you test for sulfate ions? What is the equation?

Answer 28

Add BaCl2

Question 29

Describe the method of using braium salts to test for barium sulfates. What are the results? What is the equation and the ionic equation?

Answer 29

Method:

• To 1cm3 of unknown solution
• Add 1cm3 of HCl (o remove any other ions such as carbonates)
• Add 1cm3 of BaCl2

Results: If sulfates are present a thick white ppt will form

Question 30

What is a use of barium sulfate?

Answer 30

Barium meal

BaSO4 is good at absorbing X-rays allowing the gut to be clearly seen on the X-ray

Question 31

How can calcium compounds be used for flue gas desulfurisation? Include equations.

Answer 31

CaO (or CaCO3) neutralise SO2, which is acidic, and is produced during combustion of fuels from sulfur imputities.